Killua Zoldyck is a central character in Hunter X Hunter, although his absence from the manga-0nly Dark Continent Expedition arc and the Succession Contest arc has raised a few doubts. Regardless, he is Gon Freecss' closest friend; the two boys are inseparable for nearly the entirety of the anime storyline.

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During his adventures with Gon, Killua has displayed an astonishingly vast range of emotions, from anger and jealousy to enthusiasm and playfulness, making him a fan favorite. In fact, Killua has consistently ranked at the top of every popularity poll for Hunter X Hunter characters to date — and for good reason.

10 Killua's General Opinion Of Gon

Killua, Gon, and Biscuit on Greed Island in Hunter X Hunter

Killua treasures Gon beyond measure, a feeling that is reciprocated equally. However, given his childhood experiences, it's quite surprising to see someone like Killua open his heart to another human being.

Biscuit says that he might desert his best friend in the future, but he makes a radically different choice when faced with potential death or saving Gon. He recalls their time spent together through a montage of happy memories before he perceives Illumi's manipulative needle lodged in his forehead. Such is the impact that Gon has on Killua.

9 Killua Knocks Gon Unconscious When Neferpitou Pounces

Killua saves Gon from Neferpitou Hunter X Hunter

Neferpitou, the Royal Guard in charge of security, notices Kite passing within range of their En, with Gon and Killua in tow. They leap several hundred meters before anyone realizes what's happening, severing Kite's arm in a flash.

Seeing his beloved mentor injured triggers Gon's rage problems, forcing him to emit copious amounts of aura while screaming at Pitou. Thankfully, before he can engage the clearly overpowered enemy, Killua knocks him out and carries him to safety. At least Kite received some measure of peace before his inevitable death.

8 He Saves Adult Gon From Postmortem Terpsichora

Hunter x Hunter — Killua watches Gon kill Pitou

When the realization that Pitou had already killed Kite during their first fight finally sinks in, Gon channels the entire reservoir of Nen at his disposal into an eerie transformation known to fans as Gon-san. In this form, he makes short work of Neferpitou, practically destroying their head and most of their body.

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However, he isn't aware that Nen techniques can strike after their original user has died in order to take vengeance. Once again, it falls to Killua to save Gon before Pitou's Terpsichora can gut him. The scene is especially touching because it works as closure and opens up new story avenues at the same time.

7 His Unbelievably Successful Attack Against Youpi

Killua attacks Youpi in Hunter X Hunter

As the physically-strongest Royal Guard, Menthuthuyoupi boasts immeasurable aura supplies, presumed to be considerably greater than even Chairman Netero's. In addition, the techniques he has at his disposal are both versatile and devastating, making a one-on-one battle with him impossible to win.

Despite Youpi's advantages, Killua successfully strikes him with his Thunderbolt before mercilessly attacking the Royal Guard using Godspeed. This display of force is unexpected, which is why it makes Killua much more engaging as a character.

6 Killua Wins The 288th Hunter Exam

Killua During The 288th Hunter Exam In Hunter X Hunter

Unlike the 287th Hunter Exam, which included spectacular candidates like Hisoka, Illumi, Hanzo, and so on, the 288th seems relatively easy. Either that or Killua has grown so strong that nobody is a match for him anymore.

In any case, he basically takes out every other hopeful without much effort, using his agility and reflexes to knock them out one after the other. His victory here showcases the sheer power that Killua possesses, improving his audience appeal while setting the stage for future battles.

5 He Triumphs Over His Mother's Will To Break Him

Kikyo Zoldyck Watching Killua's Friends In Hunter x Hunter

Kikyo Zoldyck claims to love her son Killua more than anything, and there is some merit to her assertion. The only problem is that she treats him less like a son and more like a killer, bred to do nothing but collect contracts and assassinate people.

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When Killua returns home after the 287th Hunter Exam, she watches Milluki "torture" him for several days, hoping that the pain would bring Killua to his senses. The fact that he is completely unfazed by Kikyo's psychological abuse is directly related to his new lease on life, courtesy of his friends Gon, Leorio, and Kurapika.

4 Killua Frees Himself From His Controlling Family

Hunter X Hunter's Silva Zoldyck and Killua Zoldyck Having A Conversation

During the Zoldyck Family arc, Silva permits Killua to leave the estate to go traveling the world with his friends, but secretly informs his wife that their chosen heir would come back to them at some point.

However, after figuring out that the Zoldycks had been controlling him for years, Killua actively chooses to leave his home forever. More importantly, he ensures that his defenseless sister, Alluka, leaves with him. It's always a breath of fresh air to watch a favorite character evolve into a better person.

3 He Protects Alluka With His Life

Killua carrying Alluka in Hunter X Hunter

Killua is clearly the only person in his family to have any kind of love for Alluka; the remaining members see her as either a tool or a threat, depending on the situation. He practically carries her to safety after blackmailing their parents and staking their mother's life on a successful escape.

What's significant is that Killua doesn't consider Alluka a burden: he regularly showers her with affection, a level of tenderness he rarely displays for most people. Killua's big brother instincts, though surprising, prove quite charming.

2 Killua's Relationship With Nanika Is Beyond Adorable

Hunter x Hunter — Killua hugs Nanika

Once Killua has Nanika save Gon's life, she lovingly asks him to pat her head, but he responds by asking her never to appear again, thinking banishing Nanika is the only way to protect Alluka. The Dark Continent entity is baffled by his mood change, and insists that she likes him (a lot). But Killua only repeats the order, hoping that Nanika would obey; she tearfully does.

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What he doesn't foresee is Alluka's rage at her brother's behavior, and her arguments finally convince Killua that he has to protect both of them as one. Killua then gently begs Nanika to return so he can apologize, which ultimately leads to a happy ending, all things considered.

1 Whenever He Talks About Eating Candy

Hunter x Hunter — Killua eating candy

Although Killua can turn rather dark and cruel on occasion, he acts his age for the most part. He's sassy, excitable, and impish, the stereotype of a preteen child. One of Killua's most lovable qualities is his adoration for anything sweet, especially candy and chocolates.

He even blows around 200 million jenny on various confections after earning them as a reward for his achievements at the Heavens Arena. It doesn't matter why or how Killua spends the equivalent of $1.5 to 2.1 million on candy, but that his displays of sweet tooth mania are extremely endearing.

NEXT: Hunter X Hunter: Is Alluka A Boy? & 9 Other Questions About The Character, Answered