- Old Mill Estates
- Old Morrisville
- Old Orchard
- Old Peru
- Old Pickens
- Old Point Station
- Old River Estates
- Old Saint George
- Old Town
- Oldwoods
- Ole Salem Estates
- Olin
- Oliver Crossroads
- Olympia
- Opossum Point Landing
- Ora
- Orange Grove
- Orangeburg
- Orchard Acres
- Orchard Hill
- Orchard Park
- Orrs
- Orum
- Osborn
- Oswald Park
- Oswald Place
- Oswego
- Otranto
- Otter Hole
- Otter Islands