- Ore Hill
- Oreminea
- Orners Corner
- Oaktree Hollow
- Orchard Glen
- Oxford Valley
- Ogle
- Oneida
- Oakhurst
- Oakland
- Oil City
- Onnalinda
- Oak Hall
- Old Fort
- Old Side
- Overlook Heights
- Oakbourne
- Oakland
- Oakwood Farms
- Old Covered Bridge Estates
- Oppermans Corner
- Oak Grove
- Oak Hill
- Oak Ridge
- Oklahoma
- Oshanter
- Ostend
- Onspaugh Corners
- Oakville
- Oakwood Park