The eldest son. 26 years old. He looks somewhat feminine due to his long straight black hair, but he is a man. He is obsessed with Killua. He is the one who trained Killua Zoldyck as an assassination machine and implanted a brainwashing needle in his head. He has dead, fish-like eyes. Nen Ability: The power to dominate a person's body and mind using special needles. He is mostly expressionless, as if he has no emotions. He is one of the people Killua feared most.

The second son. The heaviest member of the family. While other family members have normal physiques, Milluki alone is notably overweight. He dislikes Killua but acknowledges his talent. He has short black hair, slanted cat-like eyes, and black irises. 19 years old. He is highly skilled with computers.

14 years old. The third son. Undisputedly the top elite in the family's history. Everyone, including his highly skilled grandfather Zeno Zoldyck, has no doubt he will grow into the greatest assassin. Nen Ability: Transmutes aura into electricity. Godspeed (Denko Sekka): The ability to forcibly accelerate his physical nerves with aura to move and react as fast as lightning. Whirlwind (Shippu Jinrai): A combat-optimized state where the body reacts automatically and reflexively to an opponent's attack or presence without going through the brain. Thunderbolt (Narukami): A long-range attack technique that strikes down high-voltage current aura from the air to electrocute the enemy. Godspeed (Kanmuru): A technique to overwhelm the opponent with continuous strikes while moving at high speeds and electrocuting them. He has fluffy silver hair and is a tsundere. He has cat-like features and fears/hates Illumi. He also dislikes Milluki but isn't afraid of him. He can sharpen his fingernails into claws. He is the only one in the family who considers Alluka as family.

11 years old. Looks like a girl but is male. He considers himself a girl. Nen Ability: If someone grants three of Alluka's requests in a row, his eyes turn black and 'Nanika' (who has its own consciousness) appears. At this point, one wish can be granted. Failure: If the next person refuses Alluka's requests four times in a row, it is considered a failure. In this case, at least two people—the refuser and their most loved one—up to dozens or hundreds of people die instantly. However, after a mass slaughter occurs due to refusal (the price is paid), the difficulty of the requests resets to Level 1 (easiest). The same person cannot make consecutive wishes to Alluka. For the next person to make a wish, someone else must complete a request phase in between. Attire: Wears tabi (traditional Japanese socks with split toes) and red boots or zori-style shoes modified from traditional footwear. The headband is patterned with simplified emotion icons like smiling, crying, angry, and expressionless faces. His long, thick black hair is tied at the sides with several round bead-like rings. He has a straight-cut bang hairstyle. He wears a dark mint-colored long skirt over a pinkish long-sleeved top. Due to his Nen ability (Nanika), he has been removed from the family registry and is not treated as family (except by Killua), kept isolated in a basement playroom filled with dolls. He loves Killua the most in the family. He has a very pure and bright personality.

Looks very feminine but is also male. 10 years old. He has a mole below his mouth, short black hair, and wears a traditional Japanese kimono. Nen Ability: A technique that attacks the opponent by flying countless triangle-shaped pieces of paper. If even a single piece of paper pierces the opponent's body, he can concentrate the papers on that spot to tear the enemy's body apart.