Ok
- Oka, Quebec, Canada
- Okanagan-Similkameen C, British Columbia, Canada
- Okanagon Lake, British Columbia, Canada
- Okat, Canada
- Okat Vicinity, Canada
- Okavango Swamps, Botswana
- Okawachi-Yama, Saga, Japan
- Okayama, Japan
- Okene, Nigeria
- Okinawa, Japan
- Okkak, Labrador, Canada
- Oklahoma, USA
- Okressa, Sri Lanka
Ol
- Old Burial Ground, British Columbia, Canada
- Old Crow, Yukon, Canada
- Old Crow, Yukon Territory, Canada
- Old Fort, North Arm, Great Slave Lake, Northwest Territories, Canada
- Old Hootznahoo, Admiralty Island, Alaska, USA
- Old Kasaan, Alaska, USA
- Old Kasaan, Prince of Wales Island, Alaska, USA
- Old Musqueam, Musqueam North, British Columbia, Canada
- Old Orchard Park, British Columbia, Canada
- Olga Strait, Sitka Borough, Alaska, USA
- Olinala, Guerrero, Mexico
- Ollantaytambo, Cuzco, Peru
- Olorgesailie, Rift Valley, Kenya
- Olrik's Bay, Greenland
- Olubus, Papua New Guinea
- Olympia, Washington, USA
OmOnOo
- Ooldea, South Australia, Australia
- Oominovi, Greenland
- Oonalaska, Unalaska Island, Fox Islands, Aleutian Islands, Aleutians West, Alaska state, USA
- Ootsa Lake, British Columbia, Canada
- Ootsa Lake, Canada, British Columbia, Canada
- Ootsa Landing, British Columbia, Canada
- Ootsa Landing, Canada, British Columbia, Canada
OpOr
- Oraibi, Third Mesa, Arizona, USA
- Orcas Island, San Juan County, Washington, USA
- Oregon, Missouri, USA
- Oregon, USA
- Oregon Aivilik, Kinipetu USA, Canada
- Oregon state, USA
- Oregon Territory, USA
- Oriente, Ecuador
- Orissa, India
- Oriximina, Para, Brazil
- Orleans, California, USA
- Ormidia, Cyprus
- Oro, Papua New Guinea
- Orokolo, Gulf, Papua New Guinea
- Orroyo, Peru
- Oruro, Bolivia
OsOt
- Otago, New Zealand
- Otavalo, Ecuador
- Otawa, Ontario, Canada
- Oton, Iloilo, Philippines
- Ottawa, Ontario, Canada
- Otuzco, La Libertad, Peru
OuOvOwOxOyOzPa
- Pacajes, La Paz, Bolivia
- Pacasmayo, La Libertad, Peru
- Pachacamac, Peru
- Pacific County, Washington, USA
- Pacific Islands
- Padua, Tuscany, Italy
- Paete, Laguna, Philippines
- Pahuska, Central Plains, Oklahoma, USA
- Pahuska, Oklahoma, USA
- Pahuska, Osage Village, Oklahoma, USA
- Paiella, Enga, Papua New Guinea
- Paita, Peru
- Paita, Piura, Peru