Oni (鬼 (おに)) is a kind of yōkai, demon, ogre, or troll in Japanese folklore. They are typically portrayed as hulking figures with one or more horns growing out of their heads. They are popular characters in Japanese art, literature, and theatre, and appear as stock villains in the well-known fairytales of Momotarō (Peach Boy), Issun-bōshi, and Kobutori Jīsan.