Since the manga's beginning in 1998, the Hunter x Hunter series has raised the bar incredibly high for shounen anime. The lovable protagonists, well-written antagonists, and thought-provoking power systems contribute to this series' success and praise.
The series excels at making each character morally gray. Sometimes one of the good guys will do something morally wrong, and sometimes a villain will act right. These characters are typically the ones who induce a feeling of weariness and goosebumps in the audience.
Note: This list only includes characters from the 2011 anime adaptation. Beware of anime spoilers. This list is also subjective and reflects the author's opinions.
Some of the most unnerving characters in Hunter x Hunter include Hisoka, Meruem, and more
1) Hisoka Morrow
Hisoka has many fans within the anime community. His Nen ability, Bungee Gum, is incredibly versatile and has become somewhat of a meme throughout the Hunter x Hunter fanbase. This has only added to his popularity. Despite all of the love he receives, everyone knows that Hisoka is incredibly creepy.
He is shown making very questionable and inappropriate comments towards Gon and Killua throughout Hunter x Hunter. Whenever Hisoka is on screen, the two know to keep their guard up around this eerie clown.
Other than being creepy towards Gon and Killua, he also has an insatiable appetite for murder. During the 287th Hunter Exam's Fourth Phase on Zevil Island, Hisoka seemed to be going through a 'murder withdrawal.' He was taken over by an overwhelming urge to kill someone and exuded incredible bloodlust.
2) Illumi Zoldyck
Illumi Zoldyck is an incredibly powerful Nen user, and as a member of the Zoldyck family, his assassination skills are top-notch. Most likely due to his training, he tends to be a very expressionless character. He went through most of the series without showing any emotion, regardless of the situation he is in. In fact, one of the only moments where he revealed his true feelings is in the GIF above. This alone is one of his most unsettling characteristics, but there is more.
Throughout Hunter x Hunter, Illumi's twisted sense of brotherly love is what makes him a lunatic to many fans. He claims to love Killua dearly, but from what was shown, this could not be further from the truth.
Without either Killua's knowledge or permission, Illumi implanted a Nen needle in the middle of his brain to prevent him from fighting much stronger opponents and dying as a result. He would also use the needle to forcibly bend Killua to his will, and he tried to block Killua's path towards character development by tormenting and gaslighting him constantly.
3) Gon Freecss
Gon is one of the four main characters in Hunter x Hunter, and his happy, go-lucky attitude had many fans fall in love with his character immediately. Throughout the series, Gon approached many of his problems with immense courage and a clear mind. Despite all of this, there were many times Gon showed a disturbing side to his personality.
Many of Gon's unsettling instances were when he was incredibly stubborn and sustained terrible injuries or almost died. His duel with Hanzo during the Hunter Exam and his fight against Genthru on Greed Island are both examples of this. However, one of Gon's most notable unsettling moments was during the Chimera Ant arc.
As Pitou healed Komugi on Meruem's orders, Gon threatened to kill Komugi. While pointing at Komugi's body, he said:
"The next time your try to delay me, I'll kill her."
Gon's statement shocked fans. Nobody expected him to threaten someone that had no significance in his life. It was a complete 180 from the gentle Gon that everyone was used to.
When Pitou finally finished healing Komugi, Gon's anger finally reached its peak and exploded. He transformed into 'Adult Gon' and had an exceedingly dark aura and exuded a bloodlust comparable to Meruem himself. Fans went berserk at this transformation and Pitou's subsequent demise.
4) King Meruem
When he was first born, Meruem believed he was better and more important than everyone else. He even showed no remorse for his mother after she died giving birth to him. This indicated to fans that Meruem was going to have a lot of terrifying moments throughout the rest of the arc.
While being escorted by his royal guards, Meruem's first interaction with humans was on a farm. They came across a little girl, but upon seeing them, she froze in terror. She had every right to be scared as only a few moments later, Meruem decapitated her with his tail and consumed her brain.
There are many more instances like this in the Chimera Ant arc, especially with Nen users. However, once he met Komugi, he became aware of the value of life and completely changed his personality.
5) Isaac Netero
Everybody loved Isaac Netero. When he died, the fanbase was incredibly upset. He was the Hunter x Hunter version of the 'powerful elder' character trope in anime. Despite being pleasant throughout the series, he became absolutely terrifying mere moments before his death.
During the Extermination Team's raid on the Chimera Ants, Netero decided to fight Meruem. He was able to ward off many of Meruem's attacks by striking him with his Guanyin Bodhisattva at a speed faster than sound. However, thanks to his immense durability and endurance, Meruem was able to hit Netero a few times and injure him greatly.
As a last-ditch effort, Netero used the Poor Man's Rose. But before he used it, he made sure to show Meruem the true terror of the human race. The narrator even stated that the moment Netero was talking to Meruem before he activated the Poor Man's Rose was the first time the Chimera Ant king had ever felt fear.
Genthru was the main antagonist of the Greed Island Arc and was more well known as the Bomber. Everything about Genthru made fans' skin crawl. First, his incredibly sharp chin and rounded glasses give him the classic villain look.
His visible shift from a nice, caring personality to one that lacks compassion and enjoys murder was also quite terrifying. Another unsettling trait was how easily he manipulated everyone he met on Greed Island. Nobody suspected him of being the Bomber until near the end.
Shaiapouf, typically known as Pouf, was one of Meruem's Royal Guards and always had the King's best interests at heart. At first he was normal. He was always calm and adopted a stoic nature as Meruem's plans for world domination continued forward. However, all of this changed when Meruem met Komugi.
After playing Gunji with Komugi many times, Meruem began to question his stance on the human race. He viewed them as inferior beings but now was not so sure. Once Pouf noticed this, he lost all of his composure as he tried to steer Meruem away from caring for humans and fulfill Meruem's orders that seemed to contradict their very nature.
Pouf's intense violin solo was a testament to the inner turmoil he experienced. The slow and steady degradation of Pouf's sanity left fans both perplexed and unnerved.
8) Killua Zoldyck
Killua changed a lot throughout the series. With each story arc came immense character development.
He was an instant sensation amongst fans while also being unsettling. He would kill random people without a moment's hesitation. One such time was when he killed Johness in Trick Tower by skillfully removing his heart without making a mess. This both impressed fans and freaked them out.
Another moment was when he bumped into a group of Hunter Exam participants on the Hunter Association's Zeppelin. He tore them apart with his bare hands without breaking a sweat.
Neferpitou, or Pitou, was the oldest and strongest of Meruem's three Royal Guards. They were able to come out unscathed from a direct hit from Meruem's tail and Netero's Guanyin Bodhisattva. Clearly, they had immense power and durability. These traits also allowed them to wreak havoc on Nen users.
Pitou was more of a scientist during the early episodes of the Chimera Ant arc. They would kill Nen users and perform experiments and dissections on their bodies. However, one of Pitou's most heinous moments was probing Pokkle's brain while he was still alive. They did this to test out the human nervous system. Many fans recoiled in disgust when they witnessed this.
Next was Pitou's most significant battle, their fight against Kite. This was where Gon, Killua, and the audience were first introduced to the true horror of the chimera ants. Pitou easily tore off Kite's arm and killed him. After the fight, they were seen holding and patting Kite's decapitated head in their lap like it was a trophy.
10) Alluka Zoldyck/Nanika
Alluka is a kind and caring character, despite how her family, besides Killua, treated her. The other being residing in her body is Nanika. It is a creature who came to possess Alluka through unknown circumstances. Although all Nanika seeks is love and praise from those it cares about, its wish-granting ability has made that difficult for both it and Alluka.
In order to use this ability, Alluka requests something from someone three times. If the request is fulfilled, a wish will be granted. If these requests are denied, that person will be killed. This has happened to many of the Zoldyck family staff in the past.
Some had their bodies crushed to the point where they were unrecognizable, one person had her head, and at one time, 67 people were killed simultaneously. These deaths surprised fans and frightened many Hunter x Hunter characters.
To wrap up
Hunter x Hunter is a top-tier shounen anime with some incredibly complex yet dark themes. Many characters in the show not only ignore the concept of human morality, but some also are not even aware of its existence. Many issues stem from this fact and help fuel the storyline.