Killua Zoldyck

"Assassination — It's the family trade. We all take it up. My folks see me as an exceptional prospect. But I don't see that I should have to live up to their expectations."

- Killua Zoldyck

Killua Zoldyck is the deuteragonist of the anime/manga series, Hunter × Hunter. He is the middle child of the Zoldyck Family and best friend of Gon Freecss.

He is voiced by Kanako Mitsuhashi in the Japanese version of the 1999 anime and Annika Odegard in the English version, while in the 2011 anime he is voiced by Mariya Ise in the Japanese version and Christina Valenzuela in the English version.

History
Killua was born as the middle child to a family of known assassins, the Zoldyck Family. Showing great promise from birth, Killua has already mastered many killing techniques at a tender age, and is set to be one of the best assassins the family has ever produced. Bored and tired of killing, Killua unexpectedly rebelled against his family, injured 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. 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. 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 has been accepted to the 200th floor, he bailed out).

Personality
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, as he spent almost 200 million Jenny on snacks when he was at the Heavens Arena. His favorite snack is chocolate, specifically the 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 Killua 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. Killua lost, and 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.

Abilities & Powers
Yo-Yos: During the Greed Island story arc, Killua begins using yo-yos made of a special metal alloy in combat. The yo-yos are extremely durable and heavy, each weighing 50 kilograms. They can be used in conjunction with Killua's Hatsu as well. Killua is reluctant to use the yo-yos in combat, thus using only his raw physical abilities in order for his opponent to know as little about his combat abilities as possible.

In the manga the yo-yos have a six point star or hexagram design on them. The hexagram design is used in many various religions and cultures including Islam, Christianity, Occultism, Hinduism and especially Judaism where the hexagram is the symbol used for "The Star of David". In the Greed Island OVAs t

he Hexagram or Six Point Star is changed into a Pentagram or a five point star. However, later in the Chimera Ant arc, Killua is seen using a yo-yo that has a pentagram on it. Since Killua has two yo-yo it is most likely that one yo-yo has a hexagram while the other has a pentagram.

Immense Strength: Killua has displayed his strength on many several occasions. Before he learned Nen, he is able to open a 16-ton gate and after he learned it, he opened almost around 64 tons. He can also lift up boulders several times of his size with ease.

Enhanced Speed and Reflexes: Killua has shown to possess great speed on par with Gon's (when Killua is not using Nen) and has shown great reflexes reacting to the slightest amount of danger swiftly. With his speed and agility he can create multiple afterimages of himself and disappear out of sight.

Master of Stealth: Killua is very proficient in hiding and spying. Melody a hunter renowned for her hearing has said that she can hardly hear Killua's footsteps even when he was running along side with her.

Expert Tracker: He chased Nobunaga and Machi around a town with the two of them failing to spot him (although they clearly sensed his presence).

Enhanced Agility: Killua is very agile, as he can attack from every position. His swiftness is mainly employed to dodge the enemy's attacks and react immediately after being hit.

Enhanced Stamina: Killua due to his assassin training is indefatigable. He can withstand wearing battles, training sessions and runs.

Resistance to Poison: As member of the Zoldyck family, Killua was trained and became resistant to almost all kinds of poisons. He once displayed this ability when he asked Tonpa during the Hunter Exam for more juice, which contains poisons.

Electric Resistance: As a child, Killua was trained to endure large amounts of electricity. His older brother Milluki often electrocuted him for training and punishment. Killua once stated that even though he has strong resistance against electricity, he is still able to feel the pain. Due to this, Killua developed his Nen ability to electricity.

High pain resistance: Due to being tortured since he was basically born Killua has shown to be impervious to pain. He could take being whipped and electrocuted without flinching. Even though he doesn't react to pain he said he still feels it.

High intelligence: Killua can formulate accurate predictions on his opponent's move and has proved to be able to analyze hostile capabilities and thought patterns efficiently. He can devise effective strategies in a matter of instants. Also, Killua's years of experience can lead him to pick the best option. He can keep his cool in extremely dangerous situations.

Assassination Art Techniques

 * 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 includes adjusting his fingernails into claws. These claws are sharper than knives and can tear a limb easily.
 * Rhythm Echo: 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. 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.
 * Snake Strike: Killua move his arms with incredible speed, and cut everything which come in contact with.

Nen
As a Transmuter, Killua's most efficient in changing the form of his Nen. As such, Killua developed a Hatsu in which he transmutes his aura into electricity. This feat was both 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.