Hisoka's appearance is similar to that of a magician or jester, he's tall, light skin and fairly toned stature. He changes outfits in every story arc, usually adorned with various suit symbols on the front and back torso. He wears face paint, with a maroon star on his right cheek and a spring green teardrop on his left cheek, or alternately, a maroon teardrop on his left cheek and spring green star on his right cheek. During the 13th Hunter Chairman Election arc, Hisoka is shown to wear two earrings with ornamental hearts. During the Greed Island arc, Hisoka proudly wears his Greed Island Ring on his left middle finger.
In his first appearance in Nippon Animation's anime series, Hisoka's hair was originally blue, but after a revamp of the show, it was replaced with a red, almost neon pink color, so as to be in accordance with the manga. In Madhouse's adaptation, Hisoka has red hair and light amber eyes. During the Yorknew City arc in the manga, Hisoka dyes his hair light green. These varying differences symbolize the complexity of his Character.
Hisoka is portrayed as entirely self-serving, self-absorbed and selfish because he does whatever he likes as long as it pleases him in some way. His insatiable love for spilling the blood of powerful fighters in combat serves to fuel his sadistic desires. In order for them to grow to their full potential (so as to improve the pleasure of killing them later), Hisoka allows the main protagonists of Hunter × Hunter to live during situations wherein he is easily able to kill them. Likewise, he grows excited to meet any new characters he deems worthy of fighting or anyone with potential to be a good fighter and entertain him in the future.
With his manipulative and self-centered nature, Hisoka is essentially a sociopath. While he does like Gon, Killua, and many others, he has stated that for him, what is valuable one day could easily become trash the next, and he will not hesitate to kill anyone should they not meet his standards. He does not care for what has happened in the past as he is only interested in what could be amusing to him in the future or present. While Hisoka's nature tends to be malevolent, he isn't an indiscriminate killer. While he has no problems killing anyone regardless of age or sex, he only kills people who are in his way or people he deems "worthy". As such his character is more simply amoral than flat out evil. He will even assist the protagonists if there is "fun" in doing so or if it will make them stronger for a more entertaining fight in the future. Above all else, Hisoka cares only about having fun and a good challenge which may or may not (but mostly may) involve killing people.
Hisoka often exhibits androgynous aspects of his personality throughout the series, manifested in his wearing of women's shoes and using an alluring speech style typically reserved for females in Japanese. In the manga, he ends nearly every sentence with a suit symbol.
Hisoka's past is never explored in Hunter × Hunter. His character is an enigma that speaks little of his past because he is uninterested in it. Hisoka is a second time examinee in the Hunter Exam, having been disqualified for attempting to kill an examiner during his first attempt. In the 1999 anime adaptation, it is stated during his battle with Gon on the 200th floor of Heaven's Arena that Hisoka chewed "Bungee Gum" a lot as a child, but because his family was poor he often chewed it until it lost all flavor, and later he named his signature gum technique after the brand. In the manga and 2011 adaption, however, it is only said that he named both of his techniques after a candy brand and a chewing gum brand he liked when he was a kid. It can also be assumed that since the background checks the mafia did on Kortopi's clones revealed nothing, Hisoka, like the rest of the Phantom Troupe, is assumed to be also from Meteor city or otherwise simply not registered within any nations database at birth.