Hunter x Hunter is a popular shonen action series starring the young hero Gon Freecss, and early on, Gon made a good friend -- the assassin Killua Zoldyck, who is far more loyal to his friends than to his reclusive, eccentric family. More than once, Killua proved his loyalty to Gon as a friendly rival and ally, and that endeared him to many fans.
Killua is quite the character. He was trained as a merciless assassin and has a wisecracking, sarcastic attitude, but he is also brave and committed to doing good in the world in one battle after another. He also has his playful side, from his fondness of toys and yo-yos to his funny cat faces. In one way or another, Killua may remind Hunter x Hunter fans of similar anime characters, some of whom are just like him, or at least share one or two distinct traits.
10 Yukine Has An Attitude But Is Ready To Help (Noragami)
In the supernatural world of Noragami, the gods use weapons known as shinki to slay evil spirits called ayakashi. Curiously, shinki are not mere tools, but the souls of deceased individuals, meaning shinki are weapons that can act and speak on their own accord. The youthful Yukine is one such weapon.
Yukine is a boy with a playful but snarky attitude at times, and he and the minor god Yato annoy each other to no end. Still, when Yato's enemies come knocking, Yukine will dutifully assume the shape of a sword, and help Yato find victory. Only extreme circumstances can drive Yukine apart from Yato and Hiyori.
9 Mikey Is Vicious But Oddly Funny, Too (Tokyo Revengers)
Mikey is a tough-talking youth delinquent who can back up his bold words with incredible feats of violence when facing rival gangs in the streets of Tokyo. Mikey may not be evil, necessarily, but he is also aggressive and unpredictable at times, and he has gone into berserker mode more than once, frightening his allies and enemies alike.
Still, Mikey has his good side too, and he is intensely loyal to his allies and will gladly risk his life for their sake, even in the midst of a chaotic scuffle. Like Killua, Mikey is deadly but funny, and he's not afraid to show his childish side when he's relaxed and happy.
8 Kyo Sohma Rejected His Family & Sought New Friends (Fruits Basket)
Kyo Sohma is a fierce tsundere who refuses to let the Sohma family's zodiac curse ruin his entire life. He was born with the unfortunate housecat spirit, meaning he has serious personal baggage, even by Sohma standards. He's determined to fight back.
Like Killua, Kyo is a fierce but well-meaning boy who is much closer to his truly loyal friends and allies than his actual family. He is also aggressive and competitive, like Killua, but will sometimes relax and have fun, and get the most out of his friendships with Kazuma and Tohru Honda.
7 Sasuke Uchiha May Have Been Modeled After Killua (Naruto)
Even legendary manga artists such as Masashi Kishimoto, Tite Kubo and Eiichiro Oda, need inspiration, and it's possible that Sasuke Uchiha was inspired both by Kurapika Kurta and Killua Zoldyck. After all, Sasuke is a red-eyed ninja who hails from an entire family of elite assassins.
Sasuke, like Killua, started the story of Naruto as Naruto Uzumaki's fierce rival, until that rivalry turned sour later. Sasuke is also somewhat bitter, but can show his positive side from time to time.
6 Uryu Ishida Isn't Entirely Defined By His Quincy Heritage (Bleach)
Uryu Ishida the Quincy archer isn't quite as similar to Killua as Sasuke is, but broad similarities still exist. Uryu is a friendly but fierce rival to Ichigo Kurosaki, and like Killua, Uryu knows better than to allow his family's politics to determine his worldview. He will make friends on his own accord.
As one of the few surviving human Quincy, Uryu is "supposed" to hate Soul Reapers such as Ichigo, but Uryu rejects that idea. He became Ichigo's friend of his own accord, and that's roughly similar to how Killua rejected his strange family in favor of his first true friend, Gon.
5 Shoto Todoroki Has Family Drama & Boundless Talent (My Hero Academia)
Shoto Todoroki is a major supporting character, like Sasuke, Uryu and Killua, and he also has some family drama going on. In this case, Shoto is the product of a Quirk marriage, the controversial practice of two people marrying for the purpose of combining their Quirks to create the ultimate child. Shoto Todoroki is that child.
Shoto endured his father's tyranny for years, and he suffered a burn scar when his mother mentally snapped under the strain. Now Shoto is determined to define himself as a hero on his own merits, which is something Killua can understand. Both characters are talented but reject the families that gave them that talent.
4 Narancia Ghirga Is A Cool Punk (JoJo's Bizarre Adventure)
Narancia Ghirga is a supporting character in the Golden Wind story arc, and he has a long-ranged Stand called Aerosmith by his side. Narancia isn't as deadly as Killua Zoldyck, but both characters ended up alienated from the people closest to them, and they had to find a new friend to trust, or risk dying alone.
Narancia is a sharp-tongued and short-tempered punk like Killua, but both boys are good people deep down, and they are quite loyal to their new friends -- Killua to Gon, and Narancia to Bruno Bucciarati, who accepted him into the squad. Narancia will repay that favor with his life if he must.
3 Nobara Kugisaki Has An Attitude & Serious Talent (Jujutsu Kaisen)
It's true that Nobara Kugisaki doesn't have much family drama compared to Killua Zoldyck, but an anime character can be similar to Killua in other ways. Nobara is a supporting character who is an ally of the main character -- in this case, Yuji Itadori himself. Nobara is to Yuji what Killua is to Gon.
What is more, Nobara has the heart of a hero but the attitude of a smart-mouthed punk, and she's known for her confident but prickly personality, just like Killua. Both characters are known to save the day while calling other people stupid or worthless in the process. A backhanded savior.
2 Toph Beifong Ran From Her Family To Help Aang (Avatar: The Last Airbender)
Plenty of characters in Western animation share many traits with classic shonen and shojo archetypes, and that includes Toph Beifong, who is a bit of a tsundere in her own right. She may remind anime fans of many different characters, including Killua Zoldyck.
Toph can't tear people's hearts out of their chest, but she is known for her heroic but wisecracking attitude, and she doesn't tolerate nonsense from anyone, and neither does Killua. She also has family drama in her life, having fled her parents' estate to help Aang. Killua would understand completely.
1 Genos Is Serious But Has His Silly Side, Too (One-Punch Man)
Genos the cyborg doesn't have any serious family drama to his name, but he does take himself quite seriously in the story of One-Punch Man, which is an attitude that Killua shares. Both characters are also known for having a hidden funny side, which they express when they are relaxed or in a good mood. Half the time, Genos doesn't even realize he's being funny.
Genos' rivalry with Saitama is more one-sided than the friendly competition between Gon and Killua, but it's still heart-warming to watch, and Genos is fiercely loyal to his caped baldy friend. Like Killua, Genos chooses his own friends, and he sets high standards.