Hunter x Hunter has had plenty of memorable villains across its history. Illumi has played the manipulative older brother. Genthru was an overly-ambitious murderer. Meruem was a highly-evolved ant that looked to conquer the world and eat people. Every single one of them has been cold to the bone, and every single one of them has left a lasting impression in the fans' nightmares.
However, few could ever compare to what many call the series' main villain if not, at least, Gon Freecss' chief rival, Hisoka Morow. Hisoka has an elegant way of just getting under people's skills, whether it's just with the look in his eyes, the things he says, or the annoying way that he kills beloved characters.
10 Killed A Hunter Examiner For Just Bumping Into Him
Hisoka Morow knew how to set a good first impression within the first minute of his appearance. As all of the Hunter Exam entrants collected in the starting area, one unsuspecting entrant made the unfortunate mistake of bumping into Hisoka.
Being the gentleman that he is, Hisoka did the calm thing and made the guy's arms vanish into flower petals. This power is never seen again in the anime, but it's still a horrifying sight that immediately tells the viewer what long-time fans already knew: Never touch Hisoka.
9 Killed 20 Examinees During His First Hunter Exam
As horrifying as Hisoka's first act during Gon's Hunter Exam was, this was far from his worst rodeo. Hisoka had already built some notoriety among the Hunter Association for his previous attempt at the Hunter Exam. While someone of his skill and performance could've easily flown through the exam with flying colors, he decided that the only color that he really needed was dead.
Infamous to the other examinees and examiners to this day, Hisoka had apparently killed 20 other entrants during that exam but was only disqualified after injuring an examiner. If the other prospective Hunters were paying attention, they'd realize that Hisoka would be a much bigger obstacle than anything else the Hunter Association could pull up.
8 Killed Agon Out Of Sheer Bloodlust
There's a portion of the Hunter Exam where the entrants are tasked with stealing another person's badge and protecting their own. Losing either would mean having to collect even more of other people's badges. While others greedily kept hold of their own badges, Hisoka walked across the arena without worry, practically inviting other people to steal his badge.
Because all of the contestants at this point had already learned Hisoka's wicked way, many of them kept their distance for most of the exam. Without an outlet for his bloodlust, Hisoka's blood just boiled until he eventually just charged at the first person that he saw. It's shame, too. Agon looked like an interesting character.
7 Killed Geretta When Gon Wasn't In Danger
Little did Hisoka know, it was Gon who was responsible for stealing his badge. The little kid did his best to train and conceal his presence. With more moxie than anyone else in the exam, Gon built up the courage to actually try and steal from Hisoka, actually managing to steal the magician's tag. Unfortunately for him, another examinee, Geretta, was stalking him and took Gon's brief moment of surprise to stun him and steal his badge.
Hisoka, impressed with Gon's potential, decides to do the kid a favor and took back his badge from Geretta. Unfortunately for Geretta, Hisoka doesn't just steal things or knock people out. As nice as the gesture was, Hisoka kind of helped Gon in the most despicable way possible.
6 Sold The Phantom Troupe Out To Kurapika
While it's common knowledge to know that there is no honor among thieves, Hisoka selling out the Phantom Troupe still hits a little hard. The Troupe is comprised of a group of like-minded misfits who only aspire to help each other and steal things. As dark as they might be, the fans of the series have come to know that they really do see each other as family, despite some mild squabbles every now and then.
That's what makes Hisoka's constant betrayal of them so harsh. In the first chance that he gets, he immediately gives away as much information as he can about the spiders to Kurapika just so he can have some alone time to fight Chrollo Lucifer.
5 Lied To The Phantom Troupe
To be fair, the Phantom Troupe is lucky that Hisoka only lied to them here. Anyone seeing Hisoka's catalog of misdeeds knows that he could do much worse to a person. However, one shouldn't downplay what Hisoka does here. After Chrollo steals the ability to read the future, Hisoka manages to hide his fortune with his Nen ability, Texture Surprise. His fortune initially acknowledges that multiple ants would die soon and that he would get his chance to fight Chrollo.
However, before anyone else could read it, he changes his fortune to make it seem like he was in danger and manages to get the very people that he's trying to betray to protect him throughout the rest of this arc. Hisoka may be an evil genius, but he's still a genius.
4 Killed Several Hunters During The Election Arc
In his path to eventually fight Illumi (and maybe Killua), Hisoka helps Illumi during his attempt to catch Killua and Alluka before the two try to heal a near-death Gon. Their exploits attract the attention of the Hunter Association, given that the two kind of kill a lot of civilians along the way. Hisoka not only dispatches plenty of Hunters for Illumi but even dips his hand into the Hunter Association.
Either because the old man set the order against him or just because the clown revels in stirring the pot, Hisoka assassinates one of the major candidates in the Chairman Election, Teradein Neutral.
3 Killed Gotoh
When Gotoh first premiered, he immediately became a fan favorite. It's easy to make a guy like Gotoh a strict, no fun authoritarian over Killua. However, the stoic butler actually came off more like a kind and compassionate dad that just worried over his precious kid. A perfect fusion of strength and endearing likability, no one ever thought that Gotoh had any death flags over his head, despite them flowing like a parade as soon as Hisoka entered the room.
In his attempt to protect Killua, Gotoh took on the magician head-on and appeared to have the strength and fortitude necessary to take on the clown. However, Hisoka actually manages to kill him quickly and disgracefully in another one of his Lethal Pop Quizzes.
2 Killed Shalnark & Kortopi
While Hisoka did betray the Phantom Troupe during the Yorknew City Arc, it didn't seem like he was actually willing to kill its legs by himself. Until he does. After losing to Chrollo Lucifer in the fight that he always wanted, Hisoka takes it upon himself to change the context of his next fight with Chrollo. Removing all control from the spider's leader, Hisoka set out to eliminate the Phantom Troupe himself.
His first two victims just happened to be the tiny Kortopi and the smiling Shalnark. He ambushed them out of nowhere and left their rotting bodies propped up in the middle of a playground, sending a message to the Troupe and any unfortunate kids.
1 Killed Several Bystanders During His Fight With Chrollo Lucifer
To be fair, Chrollo Lucifer also takes plenty of blame for giving Heavens Arena a splash zone. However, it's not as if Hisoka didn't enjoy and take advantage of the fact that the audience was practically a weapon itself. In the two's long-awaited exchange, Hisoka and Chrollo Lucifer use the entirety of Heavens Arena in their epic fight to the death.
That includes the poor audience that thought they were just getting a show. Chrollo would start controlling and blowing up random bystanders. Hisoka would swat them off as if he was being served tennis balls. These two certainly do not play nice.