- OudenaardeBelgium
- Ouderkerk Aan De AmstelNetherlands
- OsornoChile
- OverijseBelgium
- OujdaMorocco
- OwassoUnited States
- Overland ParkUnited States
- OwossoUnited States
- Owings MillsUnited States
- OxenfordAustralia
- OxfordUnited Kingdom
- OxnardUnited States
- PachucaMexico
- PacificaUnited States
- PadangIndonesia
- Pacific PalisadesUnited States
- PadovaItaly
- PaddingtonUnited Kingdom