- Osprey Island
- Osprey Island
- Ohio
- Old City
- Omar
- Orient Island
- Orleans Four Corners
- Old Campbellwood Wye
- Osceola
- Otter Creek
- Oakland
- Old Orchard Cove
- Old Orchard Point
- Ossian
- Oneida Lake Beach East
- Oneida Lake Beach West
- Oneida Valley
- Oniontown
- Oakdale
- Oceanside
- Odessa
- Oxford
- Orient
- Oakdale
- Orangeburg
- Ogden Center
- Oklahoma Beach
- Ontario Beach
- Onteo Beach
- Otis