- O'Brien
- O'Neal Island
- Oak Acres Mobile Home Park
- Oak Harbor
- Oak Hollow Mobile Home Park
- Oak Island
- Oak Park
- Oak Point
- Oakesdale
- Oakland
- Oakridge Manor Mobile Home Park
- Oaks Mobile Home Park
- Oakville
- Obstruction Island
- Ocean City
- Ocean Grove
- Ocean Park
- Ocean Shores
- Ocean View Mobile Home Park
- Oceanside
- Oceanview
- Ocosta
- Odair
- Odessa
- Officers Row
- Offutt Lake
- Ohlers Island
- Ohop
- Ohop Bob
- Oil City