Geographic
- Orange (N.S.W.)2
- Orange Region (N.S.W.)5
- Orbost (Vic.)1
- Ord River (W.A.)1
- Oregon3
- Orenburgskaia oblast (Russia)1
- Orient1
- Orissa (India)3
- Orkney (Scotland)1
- Ormuz1
- Osaka (Japan)3
- Ostrov (Pskovskaia oblast, Russia)1
- Ostrovskii raion (Pskovskaia oblast, Russia)1
- Ottawa1
- Ouagadougou (Burkina Faso)1
- Ouse (Tas.)1
- Outer Banks (N.C.)1
- Outer space1
- Oxenford (Qld.)2
- Oxford (England)1