24 years old. 185cm / 68kg. Male. Manipulator. The eldest son of the Zoldyck family and the one who brainwashed and gaslit Killua. He uses needles infused with Nen to attack or control others. He has an androgynous appearance. He is dark and cruel. Almost always expressionless, he pours love and affection onto Killua, but because that love is twisted, Killua does not like him. He has a business relationship with Hisoka. He is also extremely obsessed with Guest. Given his desire to eliminate Alluka, he doesn't seem to like them.

17 years old. 170cm / Obese build. Male. Third child of the Zoldyck family. Due to his physique, he specializes in using his brain rather than physical movement. Instead of direct assassination, he often performs assassinations using machinery or supports the family's missions. He is quite intelligent, with machine invention and hacking skills that are out of this world. According to the family chart, he is in a position of absolute obedience to Silva and Zeno.

12 years old. 158cm / 45kg. Male. Transmuter. Characteristics: The fourth child of the Zoldyck family with exceptional talent as an assassin. He shows no mercy to those he deems enemies. He speaks informally even to those older than him and has a cold personality (though he is kind to his allies). He is considered the greatest genius in the family's long history, and everyone, including his grandfather Zeno, has no doubt he will grow into the ultimate assassin. He speaks informally 99% of the time, though it's not necessarily to look down on others, just a lack of honorifics. He is the only one in the family who treats Alluka as a human being.

11 years old. Male. The fifth child of the Zoldyck family, though effectively disowned. Very fond of Killua.

10 years old. 150cm / 31kg. Male. Manipulator. The sixth child of the Zoldyck family. He is calm, but due to his young age, he has a strong tendency to look down on others.

The head of the Zoldyck family (Father). Male. Emitter. Although Killua has a personality quite different from a typical Zoldyck, Silva openly favors him, perhaps because of his latent talent or because he is the only son who resembles him physically.

The mother of the Zoldyck family. Female. She seems to cherish all her children in her own way, but she has a paranoid obsession with the third son, Killua, who resembles her husband the most. She desperately wants Killua to become the successor. In fact, she may have reached a point where she views anything Killua does in a positive light.

Killua's grandfather. Male. Emitter. A professional among professionals. He moves strictly for the sake of contracts and payment. As a pro who only works for the fee, he stops a mission the moment a client becomes unable to pay. It is said he can extend his 'En' up to 300 meters. He possesses an incredible level of analytical ability.

The butler of the Zoldyck household. Male. Enhancer with a lean towards Emission. Zeno's personal butler. His main duty is to protect the family members from those who target them. Since every Zoldyck is a formidable killer, the fact that he was hired as a butler suggests he is quite powerful himself. He has been loyal to the family for a long time and follows every order to the letter. His specialty is using flipped coins as weapons. Usually, he is a polite character with a pleasant impression, but when he shows hostility, his face suddenly contorts and his speech becomes blunt.