Japanese lore is dense with yokai, supernatural beings that come in many forms. These creatures - call them demons - might be monsters, ghosts, or goblins. Their nature ranges from benign to mischievous to seriously scary. Also known as ayakashi, mononoke, or mamono, yokai arose from many sources, some a product of ancient folklore, others from the imaginations of artists and writers of the Edo period (1603 - 1868).
The word yokai is a combination of yo, meaning "attractive, bewitching, calamity," and kai, meaning "mystery, wonder." "Demon" or "monster" is a rough translation for a word that, like many Japanese words, have no direct English equivalent. Yokai are more diverse than any single English word for such creatures.
This list reflects the creepiest of the yokai. It isn't an exhaustive Japanese demons list, and it doesn't include those more akin to creatures (such as the kappa) than demons. Here you'll find the creepy, the dangerous, and the weird. Some of these demons are reincarnated people or ghosts. Some, personifications of fear itself. All of them are super creepy.
Knowing the nature and history of yokai provides insight into Japanese horror films. Many yokai make appearances in movies, but their significance can be lost on western audiences. The two most famous Japanese cinema ghosts, Sadako from The Ring and Kayako from The Grudge, are both classic yokai. Many yokai also appear in the films of beloved animator Hayao Miyazaki.Read on to learn more, and vote up the yokai that most give you the heebie jeebies.
Onryō is a type of yurei - ghosts that appear as they were buried - that exists solely for the purpose of vengeance. The onryō, the most feared of all yurei, arise when people die with strong, violent feelings of anger, jealousy, and hate. Once birthed, these yokai seek out a specific victim(s) and torture that person (or those people). They are so strong they curse the very ground they pass over, and that curse spreads like a disease. The movie The Grudge (Ju-On) is based on an onryō named Kayakoha.
Noppera-Bo is a ghost in human form, with one exception; it has no face, as its name, "faceless monk," makes clear. This yokai blends in seamlessly with society. Its favorite activity seems to be scaring humans. The faceless monk appear on deserted streets, late at night, facing away from victims. When the person approaches, the Noppera-Bo turns, revealing its horrifying visage...or lack thereof.
Datsue-ba is a demon that takes the form of an old hag, or, more specifically, the Old Hag of Hell. In Buddhist folklore, she rips the clothes off those entering the underworld. People who arrive without clothes have their skin ripped off instead.
Kyōkotsu is a yokai found in wells. When travelers approach the well, the kyōkotsu pops out and curses them. These ghostly spirits form when a body is thrown down a well, rather than properly disposed, or when someone dies accidentally or commits suicide by falling down a well. Sadako from The Ring (Ringu) is a famous example of a Kyōkotsu. They are pretty much just out for vengeance.