As one of the protagonists of Parasyte, Migi is a parasite that infected the main character Shinichi Izumi’s right hand, thus naming himself Migi. Most parasites take control of the entire host. Upon meeting Shinichi, Migi tries to burrow through Shinichi’s arm to reach his brain but gets blocked off and ends up being able to inhabit only his hand. He can transform into blades to fight or sprout eyes and a mouth to talk. Being a parasite, he has an alien mentality; very intelligent and logical but unable to empathize and has a low opinion of humanity.

Being merged with Migi gets Shinichi in plenty of trouble as other parasites target him. Plus, isn’t it just horrifying to imagine having another being control a part of your body? While Migi is not a villain, we believe he will keep you up at night!

Bondrewd is a villain in Made in Abyss. While he isn’t on screen for that long, he is certainly a memorable character. As a researcher of the Abyss, he has resorted to crime to fund his research of the gapingholee in the middle of their island hosting a variety of magical beings and artifacts. He has gone as far as experimenting on children in the hopes of finding a cure for the “curse” that affects people who go too deep into the Abyss.

He is the cause of a particular main character’s tragic backstory. Though his methods are well-known, he is often given a pass due to his exemplary results. We believe this is the most horrifying thing about him; he is a mad scientist who cannot be brought to justice!

If you have seen at least one episode of Attack on Titan, you should be familiar with the Colossus Titan, the first Titan to appear in the anime. Compared to other Titans, it is humongous. Standing at 60 meters, it is taller than the walls and it is the Titan that broke the outer gate of Wall Maria and started the plot of the anime. It appears as a giant without skin, its muscles visible. Hot steam rises from its body, and it can create explosions that can level buildings. It is a living nightmare to all the main characters of Attack on Titan who were displaced from their homes by this ravaging monster. Who wouldn’t be afraid of facing this Titan?

One of the antagonists of Demon Slayer, Enmu has a sadistic personality and enjoys the pain and suffering of humans. He views humans as little more than expendable and values their lives little, but he is also cruel to his fellow demons. He has the ability to affect dreams and likes tormenting humans by giving them pleasant dreams before turning them into nightmares. As a demon who literally gives nightmares, we think Enmu is a fitting character for this list.

Taking the final spot is Tomura Shigaraki from My Hero Academia, an action-shounen anime that features characters with Quirks fighting as either heroes or villains. As a villain, Tomura has the Quirk “Decay,” allowing him to make anything decay into ashes. This Quirk is effective on humans and inanimate items. What is truly terrifying about him is that his only desire seems to be tearing apart society and ruining the peace that one of the anime’s protagonists, All Might, the Number One Hero, has built up in Japan. Plus, his appearance is also downright nightmare-inducing. He appears as a man covered in detached hands. His face is usually not seen, but when it is, it is creepy and decrepit.