Oyama, Ōyama or Ohyama may refer to:
- Oyama, Tochigi (Japanese: 小山市), a city in Japan
- Ōyama, Ōita (Japanese: 大山町), a town in Japan
- Oyama, Shizuoka (Japanese: 小山町), a town in Japan
- Ōyama, Toyama, (Japanese: 大山町), a former town in Japan
- Mount Ōyama (Kanagawa) (Japanese: 大山), a mountain in Japan
- Oyama, British Columbia, a town in Lake Country, British Columbia, Canada
- Oyama (Japanese theatre), male actors who play female roles in kabuki theatre, also known as onnagata
- Oyama (crater), in Mars
- 14922 Ohyama, a inner main-belt asteroid
- Oyama Station, a station in Oyama, Tochigi
- Ōyama Station, stations with that name
- Oyama (Bicycle) A brand of bicycle