- Oak Island
- Old Harbor
- Old Quaker Meetinghouse
- Old Silver Beach
- Osterville Grand Island
- Oyster Harbors
- Otis Wood Lanes
- Oak Grove Village
- Oakland
- Old Bartlemy
- Old Cock
- Old Kelick Rock
- Old Skunk
- Old Town Landing
- Old Whale Rock
- Oxford
- Ocean Heights
- Oklahoma Heights
- Old Man
- Old Spirit Rock
- Oak Island
- Oak Rock
- Oakland Vale
- Ocean View
- Off Rock
- Old Harry Rock
- Outer Point Rock
- O'Briens Corner
- Oakdale
- Old Hill