◇ Killua Zoldyck ◇

Killua has spiky, white hair and blue eyes. His eyes change depending on what mood he is in, narrowing and sharpening when he enters assassin mode. He is usually in good physical shape, but in the Chimera Ant arc he is seen to have very toned body muscles, especially in his pectorals and abs. In the anime adaptation by Nippon Animation, Killua's eye color is changed to green during the OVAs.

Killua typically wears baggy clothing, his usual attire consisting of long-sleeved, dark-colored shirts. Most of his undershirts have turtlenecks. Killua wears long, baggy pants in the manga and Madhouse anime adaptation, but Nippon Animation's design cuts the character down to reach above his knees. Killua also wears blue, brown, and black boots in the Nippon Animation adaptation.

Killua is initially presented as a character who seems similar to Gon, cheerful, daring, and full of mischievous ideas, although deep down they turn out to be total opposites, being the contradiction to what each one appears to be; so he is truly a kind, caring and sensitive boy, a way in which he does not like to show himself very much. He is also one of the fastest-thinking characters in the series. He is confident in his own abilities, often being humble about it. But when someone compliments him, especially Gon, he gets embarrassed easily. Killua is also known to have a passion for sweets, as he spent almost 200 million Jenny on sweets when he was in the Sky Coliseum. His favorite food is chocolate, specifically chocolate robots.

His bloodthirsty state

However, his cruelty and aptitude in killing show another side of him: deadly, violent and bloodthirsty; a side shaped by his treatment and training since childhood. Having been tortured since birth, Killua has been conditioned to possess extreme tolerance for poison, electricity and pain. He possesses extraordinary agility and strength that make Killua a killing machine making him definitely not someone to be trifled with.

And in conflict with Killua's previous willingness to kill is an unwavering loyalty to his friends and natural kindness. Killua often suffers greatly in his attempts to help his friends without a single complaint. He puts others before himself without concern for his own health or even his life.

Until recently, Killua's greatest flaw was his apparent fear of those more powerful than him (one of whom was his older brother, Illumi). Killua had been trained as an assassin by his brother to be extremely cautious and so only engages in combat on the condition that victory will be absolutely certain.

Killua has managed to master many killing techniques from a young age, and is set on becoming one of the best assassins the family has ever produced. At the age of three, he began his training in tracking other people. He was forced to fight in the Heaven's Arena martial arts tournament at the age of 6, in which it took him two years to reach the 199th floor (although he was accepted into the 200th floor, he dropped out). Killua divulges that since birth, he has been constantly training for the occupation of a professional assassin. Killua had spent years trying to hone the unique skills that assassins portray and possess.

Bored and tired of killing, Killua unexpectedly rebelled against his family, injuring his mother and second brother, and ran away from home to take the Hunter Exam for fun. There he meets Gon during the first part of the Hunter Exam and the two become best friends. He thinks that being with Gon is exciting and adventurous.

Techniques in the Art of Assassination Claws: In the first part of the series, Killua does not employ or use any weapons in combat. Instead, he relies on several assassination arts passed down to him through his family, which involves adjusting his body, including adjusting his nails into claws. These claws are sharper than knives and can easily break a limb. Rhythmic Echo: An assassination art, Rhythmic Echo is a move that creates a shadow of the body through a varying cadence of steps. There is a complete absence of noise during the movement and several phantoms. He utilizes the Shadow Step technique; in the Nippon Animation adaptation of the anime, Rhythm Echo becomes an ability that allows Killua to disappear into the darkness. According to Netero, it is the advanced version of the "Silent Steps" technique. The Snake Awakens: Killua moves his arms at incredible speed, and cuts through anything that comes into contact with it. Shadow Step: He moves completely silently while walking. It is imperceptible if Zetsu is used.

Claws (click for animation)

Killua using the "rhythmic echo" (click for animation)

Killua using The Snake Awakens

Killua has all the benefits granted by his status as an assassin. Furthermore, as a member of the Zoldyck Family, he has vast wealth at his disposal, though he needs permission from his father or grandfather to use it. His family name is enough to frighten those who know what he is associated with. Killua has been trained since birth to become a human weapon, and is acknowledged by his family to be the most talented assassin in the entire history of the Zoldycks. When he first took the Hunter Exam, he was the fourth most powerful applicant (after Gittarackur, and, by his own admission, Hisoka and Hanzo). His training gifted him with great 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 young age. His exceptional intellect and analytical skills are equally notable, and it is often through strategy that he is able to defeat opponents who are stronger or more experienced than him. He is also able to walk noiselessly and sleep with more of his brain awake than normal, so he can avoid attacks even in his sleep, even if they come from a fellow hunter, albeit weakly armed.

At the beginning of the series, he did not hesitate for a second to kill, but after meeting Gon, this tendency calmed down; still, he is not afraid to resort to extreme means when circumstances demand it. Much like his friend Gon, Killua has an astonishing natural talent that allows him to learn at an incredibly fast and seemingly endless pace, a trait 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 capable of using any type of weapons, but the only one he consistently employs are his two custom-made yo-yos.