Killua Zoldyck

Initially, Killua is introduced as a character who seems similar to Gon — cheeky, cheerful, and full of mischievous ideas. He is also one of the most quick-thinking characters in the series. He is confident in his own abilities, often being humble about it, but when somebody compliments him, especially Gon, he gets easily embarrassed. Killua is also known for having a sweet tooth — he spent almost 200 million Jenny on snacks at the Heavens Arena. His favorite snack is 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. He possesses extraordinary agility and strength that makes him a one-man killing machine.

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). Illumi had implanted a needle in his brain during the first Hunter Exam, forcing Killua to retreat whenever any situation would potentially endanger his life. Upon extracting the needle, Killua was freed from this restraint and gained full control to make his own decisions about whether to flee or fight stronger opponents.

Killua is a young boy with spiky silver-white hair and large, cat-like blue eyes. He has a lean, athletic build from years of intense assassin training. His skin is fair, and he typically wears clothing that allows for maximum mobility in combat.

During the Hunter Exam arc, he wears a loose blue long-sleeved shirt and dark shorts. In the Heavens Arena and later arcs, he switches to various outfits — often V-neck shirts, shorts, and his signature greenish-blue turtle-neck in the Chimera Ant arc. During the Greed Island arc, he starts carrying his custom yo-yos.

His most distinctive feature is his spiky silver hair, which along with his cat-like eyes and small frame makes him appear deceptively innocent — a stark contrast to his deadly abilities. When he activates Godspeed (Kanmaru), his hair stands up and crackles with electricity, giving him an electrified, fearsome appearance.

Killua is one of the most powerful characters in Hunter x Hunter, combining assassin training with Nen abilities:

Natural Abilities:
- Immense Strength: Can open a 16-ton gate before learning Nen; after training, nearly 64 tons. Can lift boulders several times his size with ease.
- Enhanced Speed & Reflexes: Can create multiple afterimages and disappear from sight. With Godspeed active, his running speed reaches approximately 150 mph.
- Master of Stealth: Melody, a Hunter renowned for her hearing, could hardly detect Killua's footsteps even when running alongside her.
- Expert Tracker: Followed Nobunaga and Machi around a town without being spotted.
- Poison Resistance: Trained to be resistant to almost all poisons.
- Electricity Resistance: Endured years of electrocution from brother Milluki, which later enabled his lightning Nen abilities.
- High Pain Tolerance: Impervious to pain from whippings and electrocution, though he still feels it.
- Genius Intelligence: Can formulate accurate predictions, analyze opponents efficiently, and devise effective strategies instantly.

Nen Abilities (Transmutation Type — Lightning):
- Godspeed (Kanmaru): Killua's ultimate technique with two simultaneous effects:
- Speed of Lightning: Grants unfathomable speed (~150 mph), jumping ability, and agility.
- Whirlwind: Auto-reflex mode — Killua's body reacts to all attacks automatically, making him nearly impossible to hit.
- Electric Shock: Transmit electricity through physical contact, stunning even Menthuthuyoupi (a Royal Guard).
- Thunderbolt: Mid-range lightning bolt projected from fingertips — does not require physical contact.
- Lightning Palm: Short-range electrocution through palm contact.

Assassination Techniques:
- Claws: Fingernails sharpened into claws sharper than knives; can tear off limbs.
- Rhythm Echo: Creates afterimages through varying cadence of steps with zero noise.
- Snake Strike: Moves arms with incredible speed, cutting everything on contact.

Equipment:
- Custom Yo-Yos: Made of special metal alloy, each weighing 50 kg. Commonly imbued with electricity from his Nen. Extremely durable and deadly in combination with his speed.