Oga or OGA may refer to:
Places
- Oga, Akita, Tōhoku, Japan
- Oga Peninsula, Japan
- Oga, a frazione of Valdisotto, Italy
People
- Oga Atsushi, a Japanese sumo wrestler
- My Oga at the top, Nigerian Pidgin English term for "boss" or "leader"
- Aragami Oga, a virtual YouTuber affiliated with Hololive Production
As an acronym and initialism
- Office Genuine Advantage in Microsoft Office
- Oil and Gas Authority, regulator of oil and gas operations in the United Kingdom
- Old Gaffers Association
- Open Genealogy Alliance
- OGA, the IATA airport code for Searle Field airport, Ogallala, Nebraska
Other uses
- Oga (Gojoseon), a political structure in the ancient Asian kingdoms of Gojoseon and Buyeo
- .oga, an Ogg file containing audio
- Protein O-GlcNAcase, an enzyme that removes the post-translational modification O-GlcNAc