Oni (鬼), translated as "demon", "devil" or "ogre", can be referring to one of the following topics:
- The early tentative title of Nioh.
- The official codified term for the monstrosities in the Toukiden series.
- The "dark" energies and entities in the Fengshen Yanyi series.
- A member of a mystical race in the Harukanaru Toki no Naka de series.