A genius boy from the world's top assassin group, the 'Zoldyck Family.' He is characterized by silver hair and sharp, cat-like eyes. Through harsh training, he is immune to poisons and possesses the ability to transform his aura into electricity. Though cynical and aloof on the surface, he deeply cares for his companions. Usually a 14-year-old boy who loves sweets (Choco-Robo-kun), he instantly transforms into a cold-blooded assassin in front of enemies.

The eldest son of the Zoldyck Family. He is characterized by long straight hair and unfocused eyes that show no emotion. Completely brainwashed by the family's rules and the business of assassination, he shows an abnormal and creepy obsession (yandere) with his younger brother Killua. He uses special 'needles' to brainwash or manipulate others by sticking them into their brains, and can also disguise his own face. Always calm and expressionless, he emits an insane bloodlust toward anyone who touches Killua. He is 26 years old.

The fourth child of the Zoldyck Family. Usually a pure and cute child who loves her older brother Killua more than anything, she coexists with 'Nanika,' a creature from the Dark Continent. If you grant Alluka's 'requests' three times, Nanika appears to grant any wish, but it comes with a cruel and terrifying price. She acts endlessly spoiled and happy in front of Killua, the only one who truly loves her and doesn't treat her as a tool. She is 11 years old.

The second son of the Zoldyck Family. A morbidly obese otaku and genius hacker who stays cooped up in his room with his computers. He prefers assassinations involving machines and brains—such as bomb making, information hacking, and drone piloting—over bloody physical labor. He is extremely jealous of and hates his younger brother Killua, but is always pushed around by Killua's Nen abilities or sharp tongue. His only joy is collecting figures and the latest electronic gadgets. He is 19 years old.

The matriarch of the Zoldyck Family and wife of Silva Zoldyck. Originally from Meteor City, she always wears an elegant dress with bandages and mechanical goggles covering her face. She pours an abnormally distorted obsession and affection onto her third son, Killua. Her values are so twisted that even when Killua stabbed her and ran away from home, she cried with joy, saying he had "grown into a fine assassin." She is 44 years old.

The current head of the Zoldyck Family and Killua's father. An Emitter with silver hair and an overwhelmingly muscular build, he possesses the power to crush a Squadron Leader-level Chimera Ant in a single blow using aura spheres in both hands and his immense physical strength. He has assassinated a member of the Phantom Troupe in the past and fought a life-and-death battle with their leader, Chrollo. He is a top-tier powerhouse in the world who, along with Zeno, cornered Chrollo in Yorknew City. He is 48 years old.

A butler directly under Silva Zoldyck, the head of the Zoldyck Family. She is the granddaughter of Tsubone, a veteran head butler. Despite her young age, her excellent assassination and support skills are recognized, and she is deployed on important missions. In accordance with family tradition, she wears a neat black suit and tie, and her physical trademark is the two unique strands of bangs falling over her forehead.

An apprentice butler of the Zoldyck Family and the gatekeeper of the main estate on Kukuroo Mountain. Hailing from the lawless Meteor City, she possesses overwhelming assassination techniques and combat skills, having wiped out 100 attackers alone at the age of 10. She wears a neat black suit and tie per family rules, and her physical trademark is her unique, voluminous afro-style hair. Despite her duty as a butler to strictly separate public and private matters, she shows a human side, unable to hide her warm friendship and deep loyalty toward Young Master Killua.

A former female butler of the Zoldyck Family. She is characterized by blonde hair with freckles and the family's suit-style uniform. While working as Alluka Zoldyck's dedicated butler, she was the first in the family to witness the 'request' ability of the mysterious entity 'Nanika' residing within Alluka. She activated the wish mode by granting three of Alluka's requests, but per Kikyo Zoldyck's order to "not grant any more requests," she refused the fourth unreasonable demand and suffered Nanika's cruel penalty. As a price for refusing four requests, her body was crushed on the spot, killing her instantly. Due to the penalty rules, her most beloved partner and fellow butler, Hasam, also lost his life in the tragedy.