- Old Pleasant Hill
- Old River Island
- Old Saline
- Old Shell Beach
- Old Shongaloo
- Old Ten
- Oldfield
- Olga
- Oliva Mobile Home Park
- Olive Branch
- Oliver
- Oliver
- Olivier
- Ollie
- Olympic Landing
- Omega
- Omega
- One North Place
- Oneida
- Orange Grove Plantation
- Orange Harbor Island
- Orchard
- Oretta
- Orlandos Mobile Home Park
- Osburn
- Oscar
- Osceola
- Osceola
- Ossun
- Ostrica