2011 | 1999 | Manga
Killua has spiky silver hair, very light skin and blue eyes. His eyes change shape depending on the mood that he's in, narrowing and sharpening when he goes into assassin mode. Killua is fairly lean at the start of the series, due to constant physical conditioning and torture training he received when he was young. As time passes, he becomes more muscular and toned. In the Nippon Animation anime adaptation, Killua's eye color is changed to green during the OVAs. He is also often seen holding a green skateboard (turned yellow in the 2011 series).
Killua typically wears baggy clothing, with his usual attire consisting of long-sleeved and dark-colored shirts. Most of his clothes have a turtleneck. Killua wears long, baggy shorts in the manga and Madhouse animated adaptation, but Nippon Animation's character design shortened them to reach above his knees. Killua also wears blue boots, recolored brown and black in the Nippon Animation adaptation.
As a child, Killua's hair is longer, almost cascading to his shoulders. He wore a hoodie with his trademark blue coloring, grey pants, and shoes.
Initially, Killua is introduced as a character who appears similar to Gon, but different at the same time; cheeky, cheerful, and full of mischievous ideas. He is also one of the quickest-thinking characters in the series and often analyzes a situation with great ease and accuracy. He is confident in his own abilities, often being humble about it; but when somebody compliments him, especially Gon, he becomes easily embarrassed. Killua is also known for having a sweet tooth; he loves everything sweet and spent almost 200 million Jenny on snacks when he was at the Heavens Arena. His favorite snack is chocolate, specifically Chocolate Balls.
However, his ruthlessness and aptitude in killing shows the other side of him — deadly, violent, and bloodthirsty. Having been tortured since birth, Killua has been conditioned to possess extreme tolerance for poison, electricity and pain. Killua possesses extraordinary agility and strength that makes him a one-man killing machine — definitely not one to be trifled with.
Conflicting with Killua's predisposal to kill is his unyielding loyalty to his friends and natural kindness. Killua often suffers immensely in his attempts to help his friends without a single complaint. He puts others before himself without being concerned about his own health or even his life.
Until recently, Killua's greatest flaw was his fear of those seemingly more powerful than him (one of whom being his elder brother, Illumi). Killua had been trained as an assassin by his brother to be extremely cautious that he only engages in combat provided that victory is absolutely certain. This impeded him as a Hunter, as Biscuit stated more than once that victory is never certain, and that depending on the circumstances, a person has the potential to defeat a stronger opponent.
Killua especially struggles with these dueling ideologies during the latter half of the series, as he begins to encounter stronger opponents. His brother's teachings remained firmly entrenched in his mind, to a point at which Biscuit prophesied that he would one day abandon Gon because of this. Biscuit gave Killua an ultimatum: Defeat Shoot to claim the right to go with Gon and fight the Chimera Ants or in case Killua lost, he resolved to leave after Gon had recovered from his fight, protecting him in the meantime.
Finally he had to face Biscuit's prophecy when he encountered a Chimera Ant while Gon (who could not use Nen at the time) was not far off and had no way to defend himself. Killua made an attempt to save Gon. While fighting with the Chimera Ant, Killua was also battling his inner self. Preoccupied, Killua was losing to the Chimera Ant. At the last moment, Killua realized that Illumi had implanted a needle in his brain way back in the first Hunter Exam. This needle was responsible for forcing Killua to retreat and jailing himself in his comfort zone whenever any situation would potentially endanger his life. Upon extracting the needle, Killua was freed from this restraint and gained full control of his subconscious to make his own decision whether or not to flee whenever there is a need to fight stronger opponents.
Killua was born as the middle child to a family of known assassins, the Zoldycks. Showing great promise from birth, Killua followed the traditional Zoldyck training. He had already mastered many killing techniques at a tender age, and was set to be one of the best assassins the family has ever produced. At the age of three, he started his training on tailing other people. He was forced to battle in the Heavens Arena martial arts tournament at the age of 6, in which he took two years to get to the 199th floor (even though he was accepted to the 200th floor, he bailed out). Killua divulges that ever since his birth, he has been in constant training for the occupation of a professional assassin. Killua had spent years trying to perfect unique skills that assassins portray and possess.
Bored and tired of killing, Killua unexpectedly rebelled against his family, injuring both his mother and second brother, and ran away from home to take the Hunter Exam for fun. He meets Gon during the first portion of the Hunter Exam and they become the best of friends. He thinks being with Gon is exciting and adventurous.
Hunter Exam arc
Killua is one of the few rookies who make it to Zaban Tunnel. He meets Tonpa, and accepts the drink offered to him, despite knowing the drink contained a laxative. It is later revealed that Killua is immune towards poison. Satotz, the first examiner, begins the 287th Hunter Examination with a marathon run down a tunnel underneath Zaban City. Killua ends up next to Gon, and, after antagonizing Leorio for a bit, proceeds to ask how old Gon is. Upon finding out, he jumps off his board and introduces himself.
The second phase of the exam takes place in the Visca Forest Reserve, where the examinees meet Gourmet Hunters (and proctors) Menchi and Buhara. Buhara's test is to find the world's most dangerous pig and bring it back to him so he can eat it. Killua and Gon friends easily complete the task along with 70 other applicants. However, Menchi, the second examiner, baffles the examinees when she tells them to make sushi, a traditional Japanese dish, as none of them knows what sushi is. Menchi overreacts because of an examinee making them all fail as a result, no one passes, which requires Netero to intervene. The test is taken to Mt. Split-in-Half where examinees hunt for Spider Eagle eggs. At the end of this stage, there are 42 applicants left.
A Game At Midnight
The 42 remaining applicants board the Selection Committee's airship, where it is revealed that their next phase of the exam will begin at 8:00 A.M the next day. As everyone rests up for tomorrow, Killua and Gon encounter Netero. He challenges them to a game; if they win, he would issue their licenses on the spot. All they have to do is take away a ball from him—Netero also states that they can attack him however they'd like. Killua eagerly goes first but fails. Gon then takes his turn to take the ball but he also fails. Time passes and when it seems Killua and Gon have tried every possible tactic, Netero suggests they attack together. Though they come seemingly close to it at one point, Netero rockets in between them at lightning speed and takes the ball. Killua calls it quits and ends up killing two applicants in his frustration; Gon, however, decides to play until he forces Netero to use his right hand. When he succeeds in doing so, Gon collapses.
In the morning, the airship arrives at the top of Trick Tower. The forty applicants are informed that the objective of stage 3 is to get down from the tower alive within seventy-two hours. The group is forced to team up with Tonpa. The first serious test is to win three out of five matches against Trick Tower prisoners. Tonpa takes the first match with a hardened-looking criminal, and promptly gives up. Killua comments on how Bendot would have tortured Tonpa. He would probably rip out Tonpa's throat so that he will never be able to say that he surrenders.
Next, Gon faces the next prisoner, a serial bomber by the name of Sedokan, in a match to see whose candle can burn the longest. As their group struggles which candle to take, Kurapika lets Gon decide, trusting in his instincts. Killua questions this idea, but eventually agrees.  After Gon won his match, Kurapika engages in a death match with Majitani. After telling Kurapika that he is a member of the Phantom Troupe, Kurapika holds him up high in the air which forces Majitani to surrender. Leorio is next, facing a psychologist named Leroute. He loses fifty hours in a bet, after losing to her in a Rock-Papers-Scissors game.
Killua confidently faces Johness the Dissector, a man responsible for the murder of at least 146 people with his bare hands. When Johness tried to scare him, Killua bored asked about the death match. As Johness threatens him, Killua instantly rips out his heart, showing it to Johness and destroys it in front of his own eyes. In the 2011 anime, he returns the heart after Johness' death. His group mates were amazed, Killua said it was only easy to rip out his heart using his claws. Lippo, as well as Kurapika and Leorio, then find out that he is a member of the Zoldyck family. After three wins, they have to spend their lost fifty hours in a small room.
The last test consists of one big decision: there are two paths, one is too long that will take all five members but it will take them 45 hours to finish it and the other will only allow three of the five to enter. Killua favors the short one, chastising Gon for wanting to take the long path and saying that he plans on two of the three being "you and me" referring to himself and Gon. Gon thinks outside the box, and they choose the longer path, destroy the wall between the paths with axes provided so they could fight, and all five make it out.
The fourth phase is a manhunt on Zevil Island, wherein the 25 remaining competitors are required to target and acquire their prey's tag. Killua is stalked by Imori for the first three days on Zevil Island, the latter too nervous to strike. Imori's brothers, Amori and Umori arrive to assist their younger sibling but the trio is outmatched by Killua. Killua acquires the badges of all three brothers, throwing the two unnecessary ones away.
The Final Phase ends up being a tournament between the participants. Hanzo and Gon are scheduled to duel first, having been selected by the judges as being the most exceptional applicants—which perplexes Killua immensely. Though Gon is outmatched when it comes to combat, his unwillingness to submit results in victory. This further confuses Killua, whom seems almost jealous.
Killua forfeits his next two matches in arrogance, believing his opponents to be weaklings unworthy of his time. This ends up putting him up against Gittarackur, soon revealed to be Killua's older brother Illumi. Illumi spends the match questioning Killua's motives and denying their truth while mysteriously affecting the boy's psyche. Combating his brother's mind games, Killua reveals, for the first time, that he does not desire to become a Hunter. He wishes to become friends with Gon.
Illumi, taken aback, denies his statement's plausibility and threatens to kill Gon if Killua lifts a finger against him. Thus, Killua forfeits. The following match is intended to be Leorio vs. Bodoro, but Killua intervenes. He steps behind Bodoro and impales him, thereby failing the Hunter Exam for his murder. Killua leaves the exam site and heads home to Kukuroo Mountain.
Zoldyck Family arc
Gon, Kurapika and Leorio set off to Kukuroo Mountain in order to retrieve Killua. According to Zebro, Killua opened the third door of the Gates of Trial, which weighs sixteen tons. Gon and his friends stay with Zebro in order to train and to open the gates themselves. Then, they met Canary. She was assigned to never let anyone pass her post. It was also revealed that Killua attempted to make friends with her but she refuses. After heavily beating up Gon, she was knocked out by Killua's mother Kikyo, who was accompanied by Kalluto. Kikyo was there to deliver a message from Killua that he cannot see them. Before the Zoldycks leave, Gon tells Kikyo to inform Killua that they will stay there for about ten days.
Meanwhile, Killua was in the isolation room, all restrained and covered with bruises and whipping marks on his entire body, being tortured by his brother Milluki Zoldyck. It served as a punishment for running away, injuring him and his mother. He tried to cause physical pain to Killua by continuously whipping him but in no avail, because Killua was asleep the whole time. When he woke up he playfully greet Milluki, much to his frustration, Milluki whipped Killua's face, making him cough out blood. He informed Killua, about the situation of Gon, Kurapika and Leorio arriving to the estate. He tries to taunt Killua stating that he could order those three to be killed. Hearing this, Killua becomes angry and breaks one of his arms free from confinement. He threatens Milluki he will kill him if he tried to harm his friends. Fortunately, their grandfather Zeno Zoldyck came and orders Killua to leave and go see his father.
Silva and Killua were having a fatherly talk. His father asked him about the Hunter exam, the people he met, the feelings Killua felt and many more. After Silva asked him if he wants to see his friends again, he says yes. With this, Silva lets Killua go but he has to promise that he will never betray his friends. After this, Killua left and had a confrontation with his mother who tried to stop him from leaving. Killua left his mother, and reunited with his friends leaving the Zoldyck estate behind.
Later Kurapika informed Killua, Gon and Leorio about what Hisoka told him during the Hunter exam, they all agree to meet again in six months in Yorknew City, until that day comes Kurapika and Leorio depart, while Gon and Killua stayed together.
Heavens Arena arc
Killua and Gon went to Heavens Arena, where they will train and earn money at the same time. They meet a fellow fighter, a young boy named Zushi. He eventually became Killua's opponent. While Zushi was on the edge of losing, he suddenly released an amount of aura which made Killua wary and back off. It reminded him of his older brother Illumi, who seems to be using the same technique. After Zushi lost, Killua overheard Zushi's conversation with his master Wing. He was apologizing because he did not control his ability.
Killua then wondered out loud what Zushi was talking about. Gon suggested that they ask Zushi but they barely understood a word he said. Wing approached the three and volunteered to teach Killua and Gon a technique called Nen. In Wing's room, he was discussing the 4 main principles of Nen. He demonstrated how it works and Killua felt the strong power. After they lesson, Killua told Gon that everything Wing said was a lie.
They finally arrived to the 200th floor. They tried to pass a hallway but to no avail. As they tried to move forward, an employee shows herself. She informed them that they only have until midnight to register for the fight. Hisoka then shows himself. He told them they are not ready to set foot on the floor. Killua tried to fight back but Hisoka used from aura on him. Wing appears behind them and offered to teach them the real Nen. Before they left, the employee also informed them if Killua will not be able to register at the given time, he will never be able to register again.
Back in Wing's room, he demonstrated the real Nen and made Gon and Killua feel the pressure. Then Killua questioned Wing why he decided to teach them and he answered that it would be a big problem if they arrive at the 200th floor without knowing anything. Participants in the 200th floor are all capable of using Nen. After two hours, they went back to the hallway that Hisoka was guarding. While releasing some aura, Gon and Killua finally passed. After Hisoka left, they are confronted by three fighters, namely Gido, Sadaso and Riehlvelt. While registering, Sadaso handed out a contract that both Gon and Killua agree on fighting them.
When Zushi was about to be kidnapped by Sadaso, Killua appeared and assured them that Killua will let them win their match. Sadaso then carries an unconscious Zushi back to his room. Before the match starts, Killua enters Sadaso's room and threatens him. After that, Killua is declared winner by withdrawal. When Riehlvelt called Sadaso, he informed them that he will leave Heavens Arena. Rievhelt claimed that Killua will never threaten him. Killua is then seen in their room and informed them to respect the rules.
Killua's fight with Riehlvelt begins. The latter confidently attacks Killua with his electricity, but it failed. It is revealed that Killua developed a strong tolerance of electricity during his training against torture. He wins the match easily. Their training with Wing continues, and Killua found out he is from the Transformation group. After Gon's fight with Hisoka, Gon invited Killua to come back home with him in Whale Island. Killua agreed and they next set off to Gon's home.
Yorknew City arc
The third story arc reunites the main characters for the world's largest auction in a sprawling metropolis called Yorknew City. Killua, Gon, and Leorio try different methods to make enough money to buy Greed Island, a video game that could help Gon find his father.
Soon after the Phantom Troupe's attack and a price is put in some of the spider's head, Gon and Killua decide to capture them and claim the reward. A couple gives information about them  and Gon and Killua starts tracking Machi and Nobunaga Hazama. Both of them use Zetsu to avoid being noticed and follow them to a desert building. Killua tells Gon not to confront them and if they notice them, to run at full speed.
While watching, Nobunaga receives a call from someone and suddenly, both Machi and Nobunaga notices where Killua and Gon were hiding. Killua instantly runs but is stopped by Phinks, who was side-tracking them as they tracked the other spiders. Killua tries to escape using incredible speed and brute force but he is rendered useless against Phinks' strength and ultimately surrenders.
As both Killua and Gon were captured, they were brought and interrogated by Pakunoda to see if they knew the Chain Guy. As they arrive, they noticed Hisoka being a member but Killua plays indifferent so that they don't get in trouble. Gon messes up and screams at Hisoka's presence but Killua fixes it noticing that they have confronted a girl in the arm wrestling, meaning Shizuku. Nobunaga makes Gon to arm wrestle against him to the point of bleeding and when he tried to stop him, Hisoka threatens to kill him if he moves.
As they soon discover they don't have any connection to the Chain Guy, Killua suddenly realizes that this guy was in fact Kurapika. They are restrained and watched by Nobunaga because he wanted them to join the Phantom Troupe. They found the way to escape against Nobunaga and run, as they knew they wouldn't be able to defeat him.
They suddenly make contact with Kurapika and explain him the situation. They make a plan to stop them and Killua goes again to their hideout with Melody to inform Kurapika of their movements. Kurapika and Gon starts chasing them recklessly and as Chrollo Lucilfer, Shizuku and Machi realizes it, Killua replaces Kurapika before being captured again.
At the hotel, Killua and Gon overhears Kurapika's plan to escape and when the lights turned off, they quickly attacked Pakunoda and Machi but weren't able to escape them at the end. Kurapika instead captures their leader and order the other spiders not to harm them and follow his orders so they make an exchange between the hostages. At the end, Kurapika recovers his friends and thanks them for their help and apologizes for making them risk their lives.
Greed Island arc
Killua and Gon participate in an elimination test in which only the passing examinees can enter Greed Island under the supervision of the Jackpot Hunter Tsezguerra. At first, Tsezguerra denies Killua and Gon as they "cannot survive in the game". Killua and Gon leave the auction and proceed to their training. Within the remaining four days, Killua is able to develop his Hatsu by triggering his immunity in electricity using a stun gun. Taking Tsezguerra's qualifying exam, Killua easily passes the test as he shows off his new ability which surprises Tsezguerra.
As soon as Killua and Gon enter Greed Island, they are faced by Latarza who preys on newcomers. Latarza casts the spell card "Trace" on Killua in order to track them down. Killua, who is unaware of the consequences of the card, immediately reveals his blood thirst which scared Latarza, prompting him to return to Masadora. 
Killua and Gon are soon joined by Biscuit Krueger, a master and experienced teacher of Nen who trains them. During their training period, Killua exits the game in order to take part in the 288th Hunter Examination. He cruised through the exam by knocking out all of the other applicants and obtained a Hunter License. He then goes back to Greed Island and shortly returns to the real world to call Kurapika regarding Chrollo's state. After gaining some cards, Killua and the others are recruited by Kazsule to get the Patch of Shore (G.I card). When they entered the pirate's base in Soufrabi, Killua defeated Bopobo easily. Alongside Gon, he was also practicing for the games with Razor's Devils. He also participated in Razor's dodge ball tournament. He and Hisoka were the only ones who were not hit by the ball and stayed in the game for the longest time.
When Gon uses "back" to return to the infield, they made an offensive move to beat Razor. While Gon charges for his nen-enhanced punch, Killua holds the ball. The impact does major damage to Killua's hands. In the end, they win the game using the same technique but combined with Hisoka's bungee gum. While the Bombers are chasing Tsezguerra's team, Killua develops fighting strategies for Gon and Bisky since his hands were injured.
Upon confronting the bombers, Killua battles Sub. First he uses his nen ability on Sub but it isn't enough to stop him. Then he shows his yo-yo. In the end, he was able to land a hit on Sub's head. When Sub was lying on the ground, he combined his nen ability to electrocute the yo-yos. After Gon beats Genthru, they uses Breath of Archangel to heal their injuries. Gon ends up being the first person to clear the game and, as part of his reward, he is allowed to take three cards to be used in the real world. Using the card 'Accompany', Killua and Gon travel to a player under the user name 'Nigg', who they believe to be Ging. However, it ends up bringing them to Kite instead.
Chimera Ant arc
Alongside Kite, Killua and Gon briefly work as biological researchers in the country of Kakin. As they investigate a giant insect limb found on the country's shores, the group discover it came from a man-sized Chimera Ant Queen — an insect that devours other insects and animals, and then gives birth to progeny that inherit the characteristics of the different species it has eaten. The queen Chimera Ant washes up onto an autonomous nation called Neo-Green Life inhabited by a neo-luddite culture. The queen quickly develops a taste for humans and builds a colony in order to conceive both an army of offspring and a Chimera Ant King, Meruem. The Chimera Ants proceed to wipe out most of the population out before Killua, Gon, and Kite reach the nest. They are quickly thwarted by Neferpitou, the one of the King's Royal Guard whom forces Killua and Gon to retreat out of the country.
As Ants formerly under the Queen's rule rejoin the King, the Hunter Association mobilizes quickly to stop the oncoming genocide by sending in an extermination team of Hunters to East Gorteau. Distraught over the murder of Kite at the hands of the Royal Guards, Killua and Gon join the extermination team in order to take revenge for their friend. Along the way, they meet the Hunters Knov and Morel Mackernasey, Morel's students Knuckle Bine and Shoot McMahon and Knov's student Palm Siberia. Biscuit also returns to overlook Killua and Gon's training in hopes of beating Knuckle and Shoot when the students of Morel challenged them. During their training, Biscuit notices Killua's cautiousness during a battle. She tried to help him get over this fear and concludes to herself that Killua's cautiousness is a product of a smothering love from whoever who raised him.
The Queen dies during labor, and the Chimera Ant King and his Chimera Ants flee the N.G.L., secretly overthrowing the government of the nearby Republic of East Gorteau soon thereafter. Under the guise of the former king of the Republic, the Chimera Ant king initiates the process of forcibly awakening Nen in the civilians of East Gorteau in order to form his own personal army to conquer the world — resulting in the deaths of millions unable to awaken Nen.
Within the thirty days that Gon cannot use Nen, Gon dates Palm while Killua keeps a close eye on them. He confronts Rammot in the woods and battles him. During the first half of the fight, Rammot kicked and trashed Killua around as Killua cannot fight back. He keeps struggling about his curse, when his brother Illumi's voice keeps echoing in his head. Illumi's voice tells him to retreat as Killua cannot defeat stronger opponents than him. Just as Rammot prepares his final blow, Killua pulls out a needle from his head and instantly kills Rammot. He realizes that Illumi indeed placed a needle to keep him from danger.
Gon and Killua split up in order to stop the selection. While Gon is confronted with various Chimera Ants, Killua takes out Neferpitou's puppets and convinces some people that Diego has fallen. However, due to Neferpitou's plans, the odds go against him. Killua is then forced to retreat and stick back to the original plan of taking out he puppets. Neferpitou sends Leol, Flutter and Hina to go after Killua. Flutter tails Killua above and orders several insect-like Chimera Ants against him. Killua takes them out with ease but gets in trouble when faced with a sniper. The sniper uses a gun and fleas as his bullets. These fleas hit various parts of Killua's body which makes him lose blood. Killua deduces the situation and immediately runs after the sniper. The sniper lets Killua follow him until they arrive into an entrance of a cave. The sniper warns Killua that it is a trap, but in frustration, Killua quickly kills the sniper by sticking a finger on the man's head.
Ikalgo reveals himself and is attacked by Killua. When asked about Flutter's ability, Ikalgo refuses to answer and instead, planning to fall to his death underwater, breaks free from Killua's grip. Killua saves him using his yo-yo and remarks that they could have been friends under different circumstances. After saving Ikalgo, the Ortho siblings take charge of the fight and asks Coburn to stick a badge behind Killua. Once ashore, Killua gets attacked by multiple fish darts that seem to come out of nowhere. Using telepathy, the Ortho siblings inform Killua about their Nen ability which revolves around the game of darts. The siblings take their time to mock Killua and call themselves invincible. Their darts are unstoppable and don't materialize until it hits the target, making it impossible to dodge.  Killua gets severely injured from the darts as they pierce him through every part of his body, and suffers from extreme blood loss. As the death game intensifies, Killua finally disregards the idea of conserving stamina and uses the last of his strength to use his hatsu. Just as the final dart hits him (which was supposedly aiming for his head), he manages to grab it with the help of his newfound ability, a mini-version of his to-be Kanmuru, and replaces the tip of it with a suction cup. He fakes death by lying still on the ground and waits for the siblings to come out.
The siblings delight in Killua's supposed death, and swims out of the water to look at his corpse. Killua uses their vulnerability to his advantage and decapitates them. As he tries to leave the cave, he collapses from his multiple injuries and nearly dies from blood loss until Ikalgo arrives and saves him. 
Killua wakes up in an underground hospital a few days after. He contacts Gon, who was tremendously relieved of finding out Killua's condition and ends up screaming through the phone, to pay the hospital bill. As Killua leaves the hospital, he finds Ikalgo in an alley, casually telling him to go with him. Ikalgo is touched by Killua's actions as he considers an octopus like him as a friend, and decides to go with him.
Gon, Killua, Knuckle, Shoot, and Meleoron begin to strategize for the infiltration. Their plan is to make it seem as though a rebel would be merged with the crowd. When the Royal Guards focused on the crowd on the Selection Day, the group would intrude the palace and eliminate the King. However, Killua has doubts.
Debriefing on the facts, Killua reveals that the En that Knov came into contact with was that of Pouf's, not Pitou's. Since it had a window in which Knov could infiltrate without being noticed, Killua theorizes that Pitou's healing ability had to be solely concentrated on, which leads him to believe that one of the Royal Guards or King was injured. Ikalgo asserts that Pitou would only do such a thing in the King was injured. Since no one that they knew could do it, Killua concludes that the King injured himself.
As the citizens of East Gorteau begin their march to the palace, Gon, Killua and Ikalgo arrive in Knov's dimension. The combatants are ready. Killua is still unsure about the third party, believing that it could ruin all their plans.
At Morel's signal, the invasion squad infiltrates the palace via the doors that Knov set by the staircase. Everyone but Ikalgo heads towards the stairs. There, they unexpectedly encounter Youpi. Youpi immediately goes into attack mode. At that moment, Zeno's dragons break through the roof. When the group realized that if Knuckle and Meleoron, who were both invisible and undetectable, were killed by the dragons, they could stay invisible forever, Knuckle reassures them by punching Youpi. Gon and Killua rush past him on the stairs. While the two look for Pitou, they see Isaac Netero, who sees them in return at points at the room he just left. On the way in, Zeno tells Killua to judge what is happening inside for himself. They enter to see Pitou healing Komugi. At first, Gon assumes he is killing her, but Pitou's behavior leads Killua to believe he is actually trying to save her. Gon is enraged at the fact that Pitou so heartlessly murdered Kite but is healing this girl. Pitou, being unable to fight back, begs Gon to allow it to heal Komugi before doing what he wanted, going as far as to break its own arm. Killua reminds Gon that only Pitou can heal Kite, which causes Gon to hurt his feelings, although ultimately he gives Pitou one hour to heal Komugi's major wounds.
As they wait, Killua is approached by Meleoron, who informs him that Shoot has been taken out and Knuckle is fighting Youpi alone. Killua accepts to help him. Using Meleoron's invisibility, he manages to paralyze Youpi with Narukami right when he is about to kill Knuckle. Knuckle flees, and Killua, proclaiming he will strike only eight times, begins his attack on Youpi with Kanmuru, a Hatsu he had developed after his battle with the Ortho siblings. Youpi is completely overpowered by Killua's speed and is unable to fight back. Killua soon runs out of electricity, and is forced to flee. Youpi pursues him, but Killua escapes with Meleoron's ability, enlightening Youpi about the opponent's possible ability of invisibility or teleportation.
Killua and Meleoron, still invisible, see Shaiapouf splitting up. Killua finds a plug and starts recharging his electric supply. He states he will go back to where Gon is once he is done, and instructs Meleoron to discuss what to do next with Knuckle. Once he is finished, he starts heading back, but senses someone watching him. He discovers it's Palm, who has been mutated into a Chimera Ant. Reflecting that seeing her like that could lead Gon to a mental breakdown, he steps out of hiding to intercept her. Pondering that perhaps she came to him thanks to her clairvoyance, and thus remembers him, he starts to believe she might still be the same. The two speak for a bit, but when Palm asks him where Gon is, he becomes increasingly suspicious, ultimately calling her an enemy and preparing to fight her. She activates Black Widow and immediately crushes one of his yo-yos. Killua is forced on the defensive by her sheer attack power. As he defends himself, he asks Palm why she wants to meet Gon, stating that depending on her answer, he might tell her, as Gon's mind risks to shatter. Although he had no intention of letting the two meet, he ends up bursting in tears, lamenting he cannot do anything for his friend. Palm manages to recover her senses and destroys Pouf's clone, who was ordering her to kill Killua. Palm relieves his emotional pain, telling him it's thanks to his words she freed herself from the ants' control and that he is the only one who can really help Gon.
Palm and Killua reunite with Ikalgo. He asks Killua whether they would help Gon fight Pitou, but Killua notes that they wouldn't be sufficient. They regroup with Meleoron and Knuckle, and Knuckle is insistent on helping Gon. The group returns to the palace.
Time is up and Gon demands to leave, threatening to kill Komugi. Neferpitou is forced to obey. The group arrives, and Knuckle offers to use APR on Pitou, but Gon refuses. He orders them to watch Komugi as a hostage. He and Pitou head to Peijin alone to fix Kite. Killua takes charge of Komugi. Pouf's clone spots Killua, who is running away with Komugi. However, Killua's speed in Kamuro allows him to dodge the guard's attack. When Pouf's clone tries to kill Komugi, Killua understands she is his target and knocks her out to prevent her from struggling further. He takes on Pouf's clones, burning off part of his cells with electricity. The clone leaves soon afterwards. With Pouf gone, Killua takes Komugi to Palm, who tells him that Gon and Pitou are in Peijin, explaining her ability. Confused, she informs Killua that Pitou is healing its own arm instead of Kite. A clone of Pouf's appears before them and reveals it is his doing. If Komugi is not returned to him, Pitou will kill Gon. Activating Kanmuru, Killua crushes the clone. He leaves Komugi to Palm and heads to Peijin.
While getting nearer to the castle, he feels an incredible aura, and mistakes it for Pitou's at first. He finally meets Gon, who has somehow grown up and achieved an immense power, crushing Pitou. Worried by what his friend will have to pay, Killua tries to stop Gon from going any further. He manages to save him from a fatal attack by Neferpitou's corpse. Telling him he is happy, Gon goes back to fight Pitou and delivers the final blow. Palm later sees Killua carrying an unconscious Gon.
13th Hunter Chairman Election arc
With Gon in the hospital in critical condition, Killua returns home to seek help from his younger sibling Alluka, whose Nen ability can help save his friend from death. After convincing his father, Killua finally gets to see Alluka. The two siblings are happy to be reunited with each other. Killua remembers the time when he was young and Alluka displayed wish-granting abilities to their servants. Silva and Kikyo asked Killua about this to which he told.
Back to present, the three requests of Alluka are done and Killua has to make a wish. Silva, Kikyo and Milluki are watching through a surveillance camera in Alluka's room. Milluki regrets the computer wish because it was so easy. Silva glares at him and Milluki apologizes. Killua asks Silva to open the door for him and Alluka. His father refuses, saying that he has to make a wish inside. Killua makes a request to Alluka that if they are not able to leave the mountain together within thirty minutes, Alluka will kill their mother Kikyo. Alluka agrees and Silva has no other choice but to open the door. Kikyo slumps on the floor, thinking that Killua could say something so cruel, he has already grown and is somewhat proud of him instead.
Killua calls his friends back at the hospital and tells them that he's going to take care of things. He calls Gotoh and asks him about the Restriction Movements. After a while, Gotoh and Canary accompanies Killua and Alluka. Gotoh asks Killua if it is necessary to take Canary with them, he replies that Alluka is a "girl" and Canary will be able to take delicate care of Alluka. However, Silva ordered Tsubone and Amane to come with them as well. But before they could go, Alluka requested for Tsubone's pinky fingernail. She gladly fulfills the request and tells Killua that she will conceal herself for now. In that way, Alluka will be unable to make a request to other people.
On their way to meet Gon, Killua's butler Gotoh receives a call from Leorio, asking to speak with Killua. After they have an argument, Gotoh lets Killua on the phone to tell Leorio to listen. Gotoh then tells Leorio to make it so that when they arrive Gon is the only one in the hospital. Leorio can't agree with these conditions so he hands the phone over to Morel. He agrees to these conditions and says he will construct a private room for them in the hospital's enormous parking lot.
As Killua, Alluka and their butlers are on their way to Gon, Illumi calls him using a phone and asks him if had already taken out the needle in his brain. Killua verified it and his brother told him that "he will beat him at his own game". Soon after, a truck crashed into their car which causes them to fall off a cliff. Killua protects Alluka as Illumi and Hisoka watch from afar. When they decided to split up, Hisoka asked Illumi if he could kill Killua. Illumi gets angered, and warns Hisoka. In the dense forest, Killua sensed his brother's terrifying murderous aura. Amane suggests to stay away from Illumi as possible and they ran off. Killua suspects Amane as Illumi's cohort, but the latter assured him that she and Tsubone are not his enemies. She also told Killua that Silva and Zeno are not the enemies, their mission is to keep Killua safe. But Killua counters that as long as Alluka's safety is not one of their mission priority, they will remain as his enemies.
Killua uses his Godspeed ability to escape their butlers with Alluka. While running away, Tsubone is seen following them. When they stopped, Alluka asks him, "Am I a hindrance?" and "If it weren't for me, you'd be able to get along better with everyone in the family, right?" Killua reassures Alluka that everything will be well and he will always be with Alluka. After sensing that someone is actually watching them, Killua and Alluka leaves the scene.
As the two Zoldycks continue to escape, Killua uses Godspeed to escape Tsubone. But she uses her Nen ability that is fast enough to keep up with Killua. Tsubone, Amane and Canary follow them by a motorcycle but Killua escapes them by jumping off the cliff where the motorcycle can not follow them. He later reaches an airport and rides an airship in order to escape Illumi who is probably watching them from afar. Killua calls Morel about his plan on "selling" off Illumi. Morel thinks Teradein Neutral and Bushidora Ambitious will consent to it and many other Hunters would like to lend a hand. They plan on capturing Illumi's needle humans first. The other Hunters agree on this plan and whoever comes close to the airship will be captured. And Illumi makes his first move by using his needle humans.
Killua then contacts Canary while still inside the airship. He asks her to tell Hishita, another Zoldyck butler to send out cars to three locations as well as near the hospital where Gon is. Killua and Alluka land where Hishita is waiting with a car. Killua tells Hishita to drive them to the hospital but then needle-controlled humans appear and surround the car. Killua is surprised at how his brother could have possibly known where they will land. He orders Hishita to continue driving, but the latter informs him that he cannot do it unless Master Illumi tells him so.
Killua finds Alluka and himself surrounded by Illumi's manipulated people. Killua out of concern of Alluka's safety has become hesitant on the idea on fighting or escaping as well as puzzled on how they were followed which was answered by Tsubone who revealed that it was due to a hidden camera that was placed on her that was being watched by their Mother and Milluki, where the latter was sending the feed to Illumi's phone. After Tsubone completed the last two requests, Alluka has entered the wish granting state but used the wish to heal Tsubone's hand instead to show Illumi that there is no harsh consequence later on when asking Nanika for a wish that requires healing and threatens Illumi that if he keeps referring Alluka as an object then he will disown his eldest brother. Hearing his explanation that there would be no risk for the family, Illumi agreed that he will now allow them to continue on their quest to save Gon but warned him that the entity called Nanika is still very dangerous and will never allow Alluka to be fully free until Killua tells him why he is the only one that can make consecutive wishes on Alluka's ability (First was the kiss after they left the mountain and the second was healing Tsubone's hand making it two wishes in a row).
Finally, Killua is able to reach the hospital. While he waits for Alluka to wake by himself, the two of them stay in Gon's room. After Alluka wakes up, Killua tells Alluka that they are in the hospital and that his friend is sick and wants to make him feel better to which Alluka responds by expressing disappointment in having to turn into "It" again and wants to stay with Killua. Killua manages to convince Alluka by saying they will always be together Killua wishes for Gon to return to normal, Alluka goes into wish granting mode to heal Gon.
After Alluka switches to Nanika, Nanika is requested Gon's hand to touch it. When Killua grabbed Gon's hand, he was shocked to see it so damaged, and he begged Nanika to save Gon. Upon starting to heal Gon, a huge energy emits from Nanika, which is so powerful that everyone in the vicinity can feel it. It is shown later that Nanika succeeded in healing Gon. Subsequently, Killua was seen still in the hospital with the unconscious Alluka in his arms with Illumi approaching. Illumi hypothesizes the conditions to activate Alluka's ability and tells Killua that if he is able to control Alluka's ability as well as Killua can, he can guarantee a minimum level of freedom for Alluka, instead of being locked in a room. However, Killua states that he is going to protect Alluka no matter what, and he wakes Nanika up and asks Nanika to make Illumi go home and Illumi is immediately teleported back to the Zoldyck's residence. Killua then requests Amane and Tsubone to leave the room too or he will ask Nanika to do the same for them. Both of them leave voluntarily. Nanika then asks Killua for a pat on the head. Killua tells Nanika not to come out anymore, but Nanika refuses, stating that Nanika likes Killua.
After a brief argument which accumulated in Killua yelling at Nanika not to come out anymore, Nanika finally and hurtfully complies. Killua embraces Alluka while apologizing to Nanika and stating that now Alluka can be free. Alluka resurfaces, but gets angry at Killua for making Nanika cry, and says that if Killua wants to protect Alluka, he should also protect Nanika. Killua regains his senses and thanks Alluka for 'waking' him up. He then asks Alluka to call Nanika out and he apologizes, stating that he was afraid of the idea of Illumi controlling Alluka and doing evil things. He states that he will protect both of them and tells Nanika not to grant any more wishes. Nanika forgives Killua and both of them embrace with tears in their eyes. Tsubone is told by Kikyo Zoldyck that the movement restriction order on Killua has been cancelled.
Killua, along with Alluka later accompany Gon to the World Tree. He informs Gon that Alluka was the who healed him, when asked why he wasn't told sooner Killua responded with "it's complicated". After he declined the offer to climb the World Tree with Gon, he tells Gon that he will be going to travel to many places around the world with Alluka and will do anything to protect both Alluka and Nanika. Alluka assures Gon that when they're done, Gon should definitely play with him again, to which Killua responds that Alluka's a good sibling and light-heartedly states that Gon has become number two now. Promising to keep in touch and to stay friends no matter what, Killua tells Gon send his regards to Ging for him, and then part ways.
Skateboard: The first time he faced the Hunter Exam, Killua brought a skateboard with him. It was able to bear the weight of five people and a wooden shelf without breaking, although it was damaged in the process. The skateboard is yellow with red wheels and a red arrow painted in the middle, reaching almost to the curved end of the deck (dark blue-green with a yellow arrow in the 1999 anime). The skateboard is also briefly seen in the beginning of Hunter × Hunter: The Last Mission.
Yo-Yos: After passing the Hunter Exam, Killua was given by Milluki two yo-yos made of a special metal alloy that he began using as a secret weapon. The yo-yos are extremely durable and heavy, each weighing 50 kilograms. Their reflective surface allows them to be used as mirrors to stealthily look behind a corner. Biscuit claims they work well with Killua's ability to turn his aura into electricity.
Abilities & Powers
Killua has all the benefits granted by his status as a Hunter. Furthermore, as a member of the Zoldyck Family, he has vast wealth at his disposal, although he needs his father's or his grandfather's permission to use them. His family name alone is enough to scare the ones that know what it is associated to. Killua has been trained since birth to become a human weapon, and is recognized by his family to be the most talented assassin in the entire history of the Zoldycks. When he took the Hunter Exam the first time, he was the fourth most powerful applicant (after Gittarackur, and, by his own admission, Hisoka and Hanzo), and the one that Single Star Hunter Menchi believed would pass. Up until the Hunter Exam, he did not hesitate a second to kill, but after meeting Gon, this tendency subsided; still, he is not afraid to resort to extreme means when circumstances demand it. Like his friend Gon, Killua has an astounding natural talent that enables him to learn at a fast rate and allegedly ad infinitum, a characteristic that piqued Hisoka's interest. His potential extends to Nen as well, as noted by Wing and Bisky. Although he primarily fights with his bare hands, Killua is able to use any kind of weapons, but the only one he employs consistently are his custom-made yo-yos. When he tried to prevent the selection, he was so confident in his strength that he claimed that tanks and fighter jets would be useless against him.
His training endowed him with near immunity to poison, high tolerance to electricity, great agility and physical strength, advanced armed and unarmed combat and stealth techniques, which he acquired at a very young age. His intellect and exceptional analytical skills are equally remarkable, and it is often through strategy that he can defeat opponents who are stronger or more experienced than him. He is also able to walk without making a sound and sleep with a larger part of his brain awake than normal, so he can avoid attacks even in his sleep, even if they come from an armed, albeit weaker, fellow Hunter. After leaving Greed Island, due to his prowess in Nen, Killua became able to blend with nature more easily, which allowed him to find multiple new species of animals at a rate that astounded Kite's companions.
Killua's main weakness used to be an inferiority complex that paralyzed him with fear and prevented him from fighting opponents that could pose a threat to him, even if their overall strength was lower than his own. Although it was originally believed to be a product of his training, it is later revealed that it was actually due to a Nen-imbued needle that Illumi had implanted in his brain. Its removal caused Killua to snap free of his brother's conditioning, thus regaining the full control of his mental capabilities in battle. This also had the effect of making his overall movements better, increasing his speed.
Preternatural Perception: Killua managed to detect Meleoron's presence in spite of the latter specializing in erasing it.
Enhanced Strength: Killua has displayed his strength on several occasions. Before he learned Nen, he was able to open a 16-ton gate and after he learned Nen, he opened the 64-ton gate. He can also easily lift up boulders several times his own size and cleave through massive trees with a single strike.
Immense Speed and Reflexes: Even without resorting to Nen, Killua is tremendously fast. He can move fast enough that his opponents may lose sight of him, and kill a target without them realizing until the fatal blow has been dealt. When he retried the Hunter Exam, he knocked out more than one hundred of applicants in a matter of minutes. His speed was on par with Gon's when he was introduced, but following the removal of Illumi's needle, Killua became able to control his movements more adept, thus growing faster. A perfect comparison between his previous and current speed is given in his fights against Rammot: while in their first confrontation the Chimera Ant managed to overpower both him and Gon through sheer strength and speed, in the second Killua ripped his head off before Rammot even realized that his opponent had moved at all. His reactions are also first-class: Killua can react to the slightest amount of danger at once, allegedly even gunshots fired at near point-blank range.
Immense Agility: Killua's mobility allows him to attack from every position, move in the enemy's blind spot, and fight on any kind of terrain. In terms of defense, Killua takes full advantage of his agility to fall back quickly, dodge the enemy's attacks and react immediately after being hit. He has an excellent sense of balance, as seen when he was shown standing with nonchalance on the back of a horse, and good coordination. He managed to dispatch a small squadron of Chimera Ants that had drawn him in the treetops and surrounded him in a few seconds, not only avoiding their attacks, but also turning them against his assailants.
Enhanced Stamina: Killua is indefatigable, both physically and mentally. He can withstand wearing battles, training sessions and runs. Not even thirty hours of continuous traveling NGL by foot and battling the armed forces could wear him down.
Enhanced Durability: Killua took no damage from being kicked in the belly by Imori. He also stated that a blow to the neck that Hanzo used to knock out Gon would only leave him stunned. Even being electrocuted with 1,000,000 volts of electricity can only cause him to feel pain. Ikalgo's bullets, while packing enough power to send Killua flying a few meters, could only pierce less than an inch of muscle.
Enhanced Endurance: Killua can bear very intense physical pain without his physical or mental abilities being impaired. He fell asleep (or pretended to) while his brother Milluki was whipping him, and did not react when the latter burned him with a cigar. He can also dislodge his joints without seeming to suffer any drawback. A better example is given during his confrontation with the Ortho Siblings, in which he had his body punctured by several darts and still managed to make calculations and prepare a strategy, even coming up with an idea for a new ability.
- Resistance to Electricity: As a child, Killua was trained to endure large amounts of electricity. His older brother Milluki often electrocuted him for training and punishment. As a result, he is able to withstand high-voltage electrical currents while retaining his full mental and physical faculties, even when suffering shocks capable of stunning Sub, a superior Nen user at the time, as well as paralyzing and hurting the powerful Menthuthuyoupi. However, he stated that even though he has strong resistance against electricity, he still feels the pain. Due to this, Killua was able to develop electricity-oriented Hatsu techniques.
Immense Poison Resistance: Due to his assassin training, Killua became resistant to a great number of poisons, toxins and chemicals. He first displayed this ability when he drank five cans of Tonpa's juice during the Hunter Exam without experiencing any side effects, despite the beverage containing a laxative that, in that dose, should have completely dehydrated him. When he was stung by Mosquito, he revealed that her toxin had absolutely no effect on his body.
Muscle and Joint Control: Killua can dislodge his joints at will in less than a second, an ability that enables him to escape from most ties. An instance is given when he dislodged his shoulders, elbows, wrists and fingers to free himself from Machi's strings.
- Claws: One of the several assassination arts passed down to Killua through his family consists in adjusting the anatomy of his hand; his fingernails turn into claws that are sharper than knives, with which Killua can sever a limb, a head or even rip out an heart with frightening ease.
Healing Factor: Killua can recover from injury faster than normal, as demonstrated when the multiple wounds inflicted to him by the Ortho siblings completely healed in only a few days.
Genius-Level Intellect: Killua's intelligence surpasses that of a normal boy his age by far. He is knowledgeable about a wide variety of topics, endowed with prodigious intuition and analytical skills. His abilities in deductive reasoning are second to those of few other characters, all of which are regarded as among the smartest in the Hunter × Hunter world. He can bear severe mental strain and still think clearly, to the point that even Hunters with more experience than him rely on his predictions before making a move; and he can come up with hypotheses and conclusions that are well beyond ordinary thinking. To match all of these impressive intellectual capacities, Killua is also an extremely quick thinker, who is capable of adapting to completely unpredicted, absurd scenarios.
Master Strategist: Killua is capable of devising complex tactics, run accurate simulations and evaluate the success rate of each of them, even in the middle of a fight. Biscuit, Morel, and Knuckle all accepted his strategies as the best. He can not only predict the general going of an operation, but also the actions of each individual, even if he has never met them.
Master Hand to Hand Combatant: In spite of his young age, Killua is one of the best male fighters in the series. He is capable of fighting on even ground with foes that are physically stronger than him or have better control over their aura. His fighting style, which is extremely versatile, aims at dealing the maximum amount of damage in the shortest time possible, striking critical points and making ample use of lightning-fast submission holds to incapacitate or kill the opponent. He can precisely knock a person out by touching a sensitive spot on their neck. Killua is particularly skilled at finding patterns in the fighting style of his adversary and at figuring out their weak spots, and at using them to exploit or create an opening with which end the confrontation. It is very rare for him to resort to combos, both because his training has led him to favor sneak attacks and careful planning and because one strike from him very often results in the death of his target. Due to the Zoldyck philosophy of never putting their lives at risk while fighting, he was also taught a wide array of defensive and escape tactics, a trait that was exacerbated while Illumi was conditioning him. Following the removal of his brother’s needle he began to take more risks when fighting, which, far from weakening him, had the effect of making his overall movements more secure and, thus, faster and more precise. He also received basic training in Shingen-ryū kung fu.
- Assassin Mode: When employing his assassination techniques, Killua enters a state of mind that helps him channel his strength and concentration for the sole purpose of slaying his opponent, increasing his combat strength. He likens the process to flipping a switch.
- The Snake Awakens (蛇活 (だかつ), Dakatsu): Killua whips his arms with incredible fluidity and speed, cleaving anything that comes in contact with them.
Master Weapon Specialist: Although he prefers to fight with only his bare hands, Killua is capable of turning any object into a lethal weapon, even if he has no familiarity with it. He won Bopobo’s challenge by drenching him in liquor and setting it afire, and killed multiple soldier Chimera Ants with the arms they wielded. Killua is also adept at using projectile-like weapons, although he has never employed any in combat. His weapon of choice are two yo-yos weighing 50 kilograms each, which he can wield with great dexterity, that amazes pro Hunter Shoot McMahon. He can use them as long-ranged weapons, to ensnare the target, grab distant objects, as a grapple, or swing them around himself to counter incoming attacks. His aura can also be channeled through them to shock a target from a distance. Killua is reluctant to use them in battle if he is unable to prevent the information from being leaked to other potential opponents, preferring to resort to his raw physical abilities and combat skills in order for his opponent to know as little about him as possible.
Master of Stealth: Killua is very proficient in hiding, spying and infiltration. Melody, a Hunter renowned for her hearing, commented that she could hardly hear Killua's footsteps even when he was running alongside her.
- Shadow Step (暗歩 (あんぽ), Anpo): Due to his training, Killua has learned to walk and run without making a sound.
- Rhythm Echo (肢曲 (しきょく), Shikyoku): An assassination art, the Rhythm Echo is a motion that creates an afterimage of the body through a varying cadence of steps. There is a total absence of noise during the movement, and multiple phantoms appear. It utilizes the Shadow Step technique; In the Nippon Animation adaptation of the anime, the Rhythm Echo is changed into an ability that allows Killua to disappear into the darkness. According to Netero, it is the advanced version of the "Silent Gaits" technique.
- Expert in Tailing: Killua chased Nobunaga and Machi around a town with the two of them failing to spot him (although they clearly sensed his presence).
Masterful Skater: Killua is extremely dexterous with his skateboard, performing acrobatic tricks with ease. He has also been shown to use his skateboard to kill a Great Stamp.
Masterful Darts Player: Killua mastered the game when he was six (or seven), with a count of 1440 points. This skill came in handy against the Ortho siblings, when he recognized the rules the brother was playing with.
As a Transmuter, Killua's most efficient in changing the form of his Nen. Just like Gon's, Killua's talent is said to be absolutely astounding, found only in one out of ten million people. Thanks to Biscuit's training, he has practiced in all the five accessible Nen types. He has also mastered the four basic techniques and at least five of the advanced ones (the exceptions being possibly In and En, although he is able to use Ren to sense incoming attacks). In normal conditions, he can maintain his Ren for three hours without difficulty. While Gon can release a bigger amount of aura, Killua is generally regarded as the one with the best control. Even Biscuit commented that she reached his degree of mastery only in her early twenties. In spite of his lack of experience, he can measure with accuracy how much aura he should employ and in which area in a split second, relying solely on the instinctive knowledge granted by his fearsome potential. He easily got ahead of Gon during their training.
Killua developed a Hatsu in which he alters the properties of his aura to make it similar to electricity. This was inspired and made possible by the years of electric shocks he received as a child, both as training against torture and as punishment from his older brother Milluki. In order to use the ability, Killua needs to charge himself by absorbing electricity through a socket beforehand. He can shock the opponent either through physical contact or while keeping his distance, channeling his aura through his yo-yos or throwing it in the form of a lightning strike. Although strong opponents receive little damage from the electricity itself, they are still left paralyzed and open to another attack. Killua can also use the electricity he creates to activate simple machines or burn sturdy objects, such as the exoskeletons of certain Chimera Ants, to make them frailer and successively break them.
|Killua's Nen Type: Transmutation|
|Type: Transmutation||Thunder Palm (|
|The first and most basic ability Killua developed. As the name suggests, Killua is able to shock an opponent by touching them with his palms.|
|Type: Transmutation||Thunderbolt (|
|Killua projects a bolt of lightning from his hand, striking an opponent with electricity from a distance after jumping into the air. While it does not inflict much damage, it is very painful and capable of stunning even targets as powerful as Menthuthuyoupi. The Japanese name of the ability, Narukami, comes from the famous Kabuki play Narukami Fudô Kitayama Zakura, in which the character Narukami transforms into a thunder god at the end of the fourth act.|
|Type: Transmutation||Godspeed (|
|Killua can change the properties of his aura to generate a surge of electricity into his own body, increasing his speed to levels that transcend the limits of his body. When he activates it, his hair, hands and feet glow with electric-like aura and his body starts to give off sparks. Anyone touching him will suffer mild shocks. This ability is very versatile. It can be used offensively to overwhelm the opponent with impossibly quick blows, defensively to block or evade attacks, or both ways at the same time. Due to it, Killua can confront opponents which normally he would stand no chance against, as demonstrated when he briefly managed to overpower two Royal Guards.
Should he wish so, he can electrocute the opponent on contact, paralyzing even enemies of Menthuthuyoupi's caliber, or burn off parts of their body by generating an electric current between his hands. However, Killua can transmute only a certain amount of aura; after a while, he needs to recharge himself by absorbing electricity. There are two applications to this Hatsu:
- (To Gon) "Let's get away from Hisoka. He wants to kill somebody, and he gets impatient. If I know it, it's because him and I are of the same race."
- (To Kurapika) "If you want, I can kill him for you. You've never killed anybody, have you? You're scared?" 
- (To Silva) "When I ignore a friend I have the ability to help, wouldn't I be betraying him?"
- (To himself) "It's the other way around. Gon, it's me... Meeting you, I'm the fortunate one."
- (To Gon) "Gon, you are light... Sometimes, you shine so brightly that I must look away.. But even so, is it still okay if I stay by your side?"
- (To himself) "What will I do when things really go wrong? Am I strong enough to be the partner Gon needs at that moment? When Gon most needs me to have this back - will I have his back?"
- (To Gon) "Gon, for the next thirty days that you can't use Nen, I will protect you. No matter what it takes, at any cost. But after that, it's goodbye."
- (To Ikalgo) "Because you're cool. Had we met under different circumstances, I think we would have been friends." 
- (To Palm) "Because we're friends, you don't need to thank friends." 
- (To Youpi) "Sorry, but what I'm about to do to you is just me blowing off some steam."
- (To Illumi) "Bring it. I'll beat you at your own game." 
Translations around the World
|Foreign Language||Translated name|
|Chinese (Hong Kong)||基路亞·祖迪|
- The Official Hunter × Hunter Character and World Databook has spelled Killua as "Killua Zaoldyeck".
- Out of the four main protagonists, Killua is the youngest; during the first phase of the Hunter Exam, he confirms that his age is almost 12, just like Gon. Gon's birthday is May 5, while Killua's birthday is July 7, making Killua younger than Gon.
- Killua ranked first in all of the three character popularity polls that have been conducted so far by Weekly Shonen Jump.
- Fans stated that his changing moods gave him a lot of points and Killua looks strong. Fans also wanted Killua as their little brother.
- Killua is the 3rd Transmuter in the Zoldyck family, after Zeno and Silva. All have silver hair as well, a trait found in all transmuters in the Zoldyck family.
- Of the four main protagonists, Killua is the only to have failed a Hunter Exam.
- Killua's name in Japanese is written as "Kirua" in katakana. It combines the Japanese transliterations of the English words "kill" (kiru) and "killer" (kira).
- Killua's eye color shifted in the 1999 series; though initially dark blue, his irises became green in the OVA series. In 2011 series, his eyes are back to dark blue.
- Killua is reported to be four centimeters (about one inch) taller than Gon, but the two are often seen being the same height.
- He once stated that he does not know how to write letters, but he had written a "death notice, Zoldyck style" before. Another kind of letter is used for blackmailing people.
- He hates red peppers. At Gon's house, Mito forced Killua to eat the red pepper, but he spit it out.
- Favorite Food: ChocoRobo-kun (chocolate balls).
- Killua is occasionally drawn with catlike features (paws, ears, mouth) in humorous situations, much like Botan of YuYu Hakusho (a previous work by the same mangaka) was.
- He is nicknamed Kil or Killu by his family. However, neither the Zoldyck's employees nor Gon and his friends use this name.
- Hiei, one of the main characters from YuYu Hakusho, bears some similarities to Killua.
- Both of them have gone through a tragic childhood, killing people at a young age and being submitted to torture.
- Just as Hiei can conjure up fire and manipulate it, so does Killua replicate the characteristics of electricity with his aura. This ability was based on the immunity Killua had developed during a long childhood of electrical torture.
- Both are extremely fast.
- Both tend to kill their opponents in the most brutal ways and lack remorse when doing so.
- Hiei was ranked on first place for most popular character in the YuYu Hakusho manga, Killua had also won first place in the Hunter × Hunter popularity votes.
- Both can use sharp objects as weapons, Hiei his sword and Killua his fingernails, but are also exceptional hand-to-hand combatants.
- Just like Hiei has black spiky hair and same colored clothing, Killua has white spiky hair and same colored clothing.
- Killua's yo-yo's may have been derived from Rinku, a secondary character of Togashi's other series YuYu Hakusho.
- In the 1999 series, Killua enjoys exploring cockpits and drinking tea.
- Still in the 1999 series, Killua was slapped two times by two different women: Mito Freecss and Biscuit Krueger.
- In the 1999 anime, he watched a porn movie in a hotel in Yorknew City.
- The 2011 series added some scenes where Killua and Canary first met as children. He also tried to make friends with Canary, but he never tried to offer her an animal skull.
- In the French version of Hunter × Hunter, Killua is nicknamed "Lukia" by Leorio.
- According to the Hunter × Hunter Official Databook, Killua's stats are:
|Hunter Exam arc||1/5||3/5||2/5||0/5||2/5||2/5|
|Yorknew City arc||2/5||3/5||3/5||2/5||2/5||2/5|
|Greed Island arc||2/5||3/5||3/5||3/5||2/5||3/5|
|Chimera Ant arc: NGL||3/5||4/5||4/5||3/5||3/5||3/5|
|Chimera Ant arc: Palace Invasion||4/5||4/5||4/5||4/5||3/5||4/5|
|Members||Gon Freecss • Killua Zoldyck • Kurapika • Leorio Paradinight|
|Members||Maha Zoldyck • Zeno Zoldyck • Silva Zoldyck • Kikyo Zoldyck • Illumi Zoldyck • Milluki Zoldyck • Killua Zoldyck • Alluka Zoldyck • Kalluto Zoldyck • Zzigg Zoldyck|
|Members||Tsubone • Canary • Amane • Zebro • Seaquant • Gotoh (former) • Mitsuba (former) • Kasuga (former) • Yasuha (former) • Hishita (former) • Hasama (former)|
|Members||Mike • Unnamed dragon|