Illumi is the eldest son of Silva. He was introduced as Gittarackur during the 287th Hunter exam then his true identity was revealed during his fight against his younger brother Killua in the final stage of the hunter exam. Illumi used the needles to change his appearance and disguised as Gittarackur during the exam so that Killua would not recognize him. Illumi had two purposes to participate in the hunter exam. the first is because his next assassination job requires a hunter license and the second is to keep an eye on his brother Killua. during the exam Illumi teamed up with Hisoka Morow.
Apart from his physical strength, agility, and resistance to poison as the rest of the family, his Nen is very strong and he is definitely falls in the Manipulation category of Nen as all of his Nen abilities are in that category. Below is a list of his Nen abilities:
Illumi performed multiple jobs as an assassin. Not all of these jobs required him to kill someone as when he took Hisoka's place, his job was only to fool other troupe member into thinking that Hisoka Morow remained at the hideout and never left. another job was when he was hired by Chrollo (the head of the spiders) to kill the Mafia's ten dons at which he teamed up with Maha and his youngest brother kalluto to successfully complete the mission.
When it comes to strength, Milluki is not a match to the other family members. He never been shown demonstrating strength or agility. Killua has stabbed Milluki in his way out when he left the family property to take the hunter exam. Milluki himself is an assassin and perform his job using poison and bombs. When Killua came back home after the hunter exam, Milluki tortured him with a whip in the torture room as a punishment.
Milluki didn't leave the family property since he was 10. He spends most of his time in his room in front of the computer. He is a genius Computer hacker and programmer. he was interested in Greed island as he was interested in the prize of winning in that game.Milluki gave up hope on this game until Killua contacted him and shared a memory card of Greed island. He then left the family property in an attempt to get a copy of that game. He failed due to not having enough money to buy the game.
Killua is one of the main characters of HunterXHunter along with Gon Freecss. He is 12 years old and slightly younger than Gon. In the Zoldyck family he is the only one who inherited the silver hair as his father and grandfather. He is considered the heir of the family to lead the Zoldyck family one day. His family has high hopes for him to be an exceptional assassin except that Killua himself does not share the same belief with the rest of his family. His father started training the named heir of the family since the day of his birth, as a result of this training, Killua was able to withstand electricity, immune to many types of poison and sedatives and gained strength with many assassination skills. At the age of six he was fighting in the heavens arena. in two years he was able to reach to the 200th floor.
At the age 12 he ran away injuring his mother and his brother Milluki in the process. Then he participated in the hunter exam not because he was interested to be a hunter. However, during the exam he met Gon and became his closest friend. They both remained together traveling, adventuring and fighting for their life together until the time Gon has met his father
Killua is very skillful with many abilities demonstrated through out the anime. Before he even learns Nen he was able to pluck out the heart of the serial killer and the fearful man called Johness the Dissector in an instance. His assassination abilities are as following
After learning Nen and discovering that he falls in the Transmutation category of Nen, he trained himself for the following abilities which are suitable for his category and all of them depends on electricity where he would need to recharge
Alluka is the only daughter of Silva and Kikyo, she is much different than the rest of the Zoldyck family, and as stated she possess the power to end the entire family. She is a normal girl and doesn't have any special strength or power and could be killed easily. However she is possessed by a creature from the dark continent which is called Nanika ( which means "Something"). It's unknown how did she become possessed with this entity. The family spent a lot of time and resources to figure out how does Nanika's power work
Alluka is locked up the entire time in a chamber at the family property with high security and many steel doors with passwords. She is being monitored with cameras all the time. Alluka is the host for Nanika which is still unknown to this point how it ended up possessing Alluka. Killua has a way of knowing whether it's Alluka or Nanika that is talking to him because Alluka would always calls him by name while Nanika keeps calling him big brother
Nanika has a power of granting wishes after fulfilling three requests given by Alluka. There is a direct relation between the wish being granted and the difficulty of the next three request. To fully understand this power and the rules to activate and control this power the family has conducted multiple experiments and there has been multiple incidents. finally they have came up with five rules for it's power of granting wishes known by the family as following
There are some rules also was known only by Killua which are:
This is the youngest child of the Zoldyck family, he is only 10 years old. He supported Illumi in killing the Mafia's Ten Dons. Also on another occasion he helped Illumi leave the phantom troupe hideout when he was covering up for Hisoka's absence. Kalluto has a very good relationship with his mother. As the rest of the family members, he is resistance to most poisons and have great strength and agility with training of assassination techniques. eventually he joined the phantom troupe replacing Hisoka as #4.
Kalluto is a Manipulator. He is well trained for Nen as demonsterated with the encounter against the Chimera ants. Two abilities are known so far