Killua Zoldyck

The third child (third son) of the Zoldyck family. Passed the 288th Hunter Exam. He is 12 years old (11 at his first appearance). His birthday is July 7th. He is 158 cm tall and weighs 45 kg. His blood type is A.

He is a close friend of Gon Freecss. Having lived a life with no interaction outside of his family and the servants, he ran away from home after stabbing his mother and second brother multiple times. He met Gon during the 287th Hunter Exam, which he took on a whim, and Gon became his first-ever friend. Since then, he has spent a lot of time with Gon. In the 287th Hunter Exam, he voluntarily disqualified himself by killing Bodoro, Leorio's opponent in the final exam, but in the 288th exam, he defeated all other participants and became the sole successful candidate.

He has been receiving elite training to become an assassin since childhood and has already accumulated numerous combat experiences despite being a boy. His talent in assassination techniques is said to be the best in the history of the Zoldyck family. All family members, except for the second son Milluki, recognize Killua as the successor of the Zoldyck family (even Milluki acknowledges Killua's talent as the best in the family), and he is respected by all the servants. Conversely, Killua finds his mother Kikyo annoying, fears his eldest brother Illumi, despises his second brother Milluki, is a bit spoiled by his grandfather Zeno, and respects his father Silva. He cherishes his fourth sibling Alluka as a "sister" to the point of being overprotective and shows intense anger when she is treated as a tool, willing to involve others to protect her.

He sometimes gets into verbal spats with Gon, but it's due to their close relationship. In the Greed Island arc's dodgeball game, despite understanding the immense strain on Killua's hands, Gon trusts him enough to say, "I can hit the ball with all my aura because Killua is holding it." Before learning Nen, he seemed to overestimate his abilities, and during the ball game with Netero, he thought he would want to kill to take the ball if it continued, leading him to kill two other examinees who picked a fight with him (in the first anime adaptation, it was one examinee, and he left them half-dead, not killing them). He also often shows a lack of courtesy, such as when he agreed with Wing's question about whether it's okay to want to kill, saying, "It's impossible." He also feels rivalry towards Gon, as seen when he was anxious upon realizing Gon had better results in the Hunter Exam.

In contrast to the straightforward and reckless Gon, Killua is calm, collected, and quick-witted, taking realistic actions to avoid danger after assessing the situation. He is sociable within the Zoldyck family. However, his occasional cowardice is not only due to his upbringing but also due to Illumi's brainwashing. After breaking free from the brainwashing, he retains his fundamental prudence but becomes more spirited and eventually parts ways with Illumi. Being inherently cautious, he sometimes has differing opinions from his companions. Despite his young age, he has a mature perspective and can be cold to those he doesn't acknowledge, even if they are family.

Due to his father Silva's conviction of "he is my child," he was manipulated by Illumi's needle to "not fight enemies he can't win against," leading him to betray Gon by fleeing from enemies and breaking his promise to his father to "not betray his friends," pushing him to become an assassin voluntarily. However, this plan failed when Killua removed the needle himself. Ultimately, the alert on Alluka and Killua was lifted, and their runaway was tacitly approved by the Zoldyck family. At one point, he showed an obsessive attitude towards his first friend Gon, but as he continued his journey, he made friends like Ikalgo without Gon's involvement and remembered his beloved Alluka, showing mental maturity. He had many appearances in the first half of the series up to the Chairman Election and Alluka arcs, especially shining in the Alluka arc when Gon was in a semi-protagonist exit state. He has grown both mentally and physically in the series, with Tsubone assuring that he "won't fall behind Illumi-sama." In the Dark Continent arc, he parts ways with Gon to protect Alluka from Illumi's pursuit.

Due to his lack of manners and slight insensitivity, he tends not to be liked by adult women, unlike Gon. In the series, he often angers Biscuit and Palm, and in the first anime adaptation, Menchi was antagonistic towards him. On the other hand, Mito treats him as a precious friend of Gon, and Killua admires Mito as an ideal mother figure (in contrast to his dislike for his biological mother). He enjoys sweets and games, having hobbies and tastes typical of children today. Having never been in financial trouble, he lacks a sense of money and is prone to gambling. When he gets into gambling, he often ends up nearly penniless.

When he returned from the 287th Hunter Exam, he could open the third door (16 tons) of the Testing Gate, but after returning from the battle with the Chimera Ants, he could open the fifth door (64 tons).