Encyclopedias, Almanacs, Transcripts, and Maps
- Odra
- Odría, Manuel
- Odum, Eugene Pleasants
- Oehlenschläger, Adam Gottlob
- Oeneus
- Oeta
- Ofen (Alpine pass, Switzerland)
- Ofen (German name for Buda, Hungary)
- Offenbach am Main
- Offner, Richard
- Offutt Air Force Base
- Og
- Ogasawara-gunto
- Ogata Kenzan
- Ogata Korin
- Ogbomosho
- Ogdensburg
- Ogé, Vincent
- Ogilvy, David Mackenzie
- Oglala Sioux