| Name | What | Region | Country | Lat | Long | Elev ft. | Pop est |
|---|---|---|---|---|---|---|---|
| O'Briens Corner | city | Massachusetts | United States | 42.09 | -72.64 | 144 | |
| Oak Bluffs | city | Massachusetts | United States | 41.45 | -70.56 | 3 | |
| Oak Grove | city | Massachusetts | United States | 42.43 | -71.07 | 45 | |
| Oak Grove Village | city | Massachusetts | United States | 41.70 | -71.13 | 134 | |
| Oak Hill | city | Massachusetts | United States | 42.26 | -71.79 | 830 | |
| Oak Hill Park | city | Massachusetts | United States | 42.29 | -71.19 | 98 | |
| Oak Island | city | Massachusetts | United States | 42.43 | -70.99 | 0 | |
| Oakdale | city | Massachusetts | United States | 42.39 | -71.79 | 830 | |
| Oakdale | city | Massachusetts | United States | 42.24 | -71.15 | 78 | |
| Oakdale | city | Massachusetts | United States | 41.76 | -70.71 | 9 | |
| Oakdale | city | Massachusetts | United States | 42.20 | -72.62 | 223 | |
| Oakham | city | Massachusetts | United States | 42.35 | -72.05 | 892 | |
| Oakland | city | Massachusetts | United States | 41.91 | -71.14 | 49 | |
| Oakland Heights | city | Massachusetts | United States | 42.23 | -71.78 | 830 | |
| Oakland Square | city | Massachusetts | United States | 42.04 | -70.80 | 98 | |
| Oakland Vale | city | Massachusetts | United States | 42.47 | -71.03 | 72 | |
| Oaklands | city | Massachusetts | United States | 42.63 | -71.29 | 147 | |
| Ocean Bluff | city | Massachusetts | United States | 42.10 | -70.65 | 3 | |
| Ocean Grove | city | Massachusetts | United States | 41.73 | -71.21 | 13 | |
| Ocean Heights | city | Massachusetts | United States | 41.41 | -70.55 | 3 | |
| Ocean View | city | Massachusetts | United States | 42.68 | -70.62 | 3 | |
| Oklahoma Heights | city | Massachusetts | United States | 41.44 | -70.61 | 49 | |
| Old Boat Point | city | Massachusetts | United States | 42.24 | -70.97 | 3 | |
| Old Cambridge | city | Massachusetts | United States | 42.38 | -71.12 | 36 | |
| Old City | city | Massachusetts | United States | 42.64 | -71.73 | 830 | |
| Old Common | city | Massachusetts | United States | 42.18 | -71.79 | 830 | |
| Old Harbor | city | Massachusetts | United States | 41.60 | -69.98 | 0 | |
| Old Hill | city | Massachusetts | United States | 42.10 | -72.57 | 196 | |
| Old Mouth North River | city | Massachusetts | United States | 42.13 | -70.68 | 3 | |
| Old North Ashburnham Station | city | Massachusetts | United States | 42.66 | -71.98 | 1056 | |
| Old Oaken Bucket Homestead | city | Massachusetts | United States | 42.18 | -70.76 | 45 | |
| Old Quaker Meetinghouse | city | Massachusetts | United States | 41.75 | -70.46 | 9 | |
| Old Silver Beach | city | Massachusetts | United States | 41.63 | -70.64 | 29 | |
| Old Spain | city | Massachusetts | United States | 42.24 | -70.94 | 45 | |
| Old Sturbridge Village | city | Massachusetts | United States | 42.11 | -72.10 | 830 | |
| Old Town Landing | city | Massachusetts | United States | 41.80 | -71.12 | 3 | |
| Olde English Village | city | Massachusetts | United States | 42.56 | -72.00 | 994 | |
| Oldham Pines | city | Massachusetts | United States | 42.07 | -70.83 | 49 | |
| Oldham Village | city | Massachusetts | United States | 42.07 | -70.83 | 98 | |
| Onset | city | Massachusetts | United States | 41.74 | -70.66 | 0 | |
| Onset Station | city | Massachusetts | United States | 41.76 | -70.68 | 9 | |
| Orange | city | Massachusetts | United States | 42.59 | -72.31 | 830 | |
| Orchard Hills Estates | city | Massachusetts | United States | 42.11 | -71.84 | 830 | |
| Orient Heights | city | Massachusetts | United States | 42.39 | -71.00 | 19 | |
| Orleans | city | Massachusetts | United States | 41.79 | -69.99 | 29 | |
| Osterville | city | Massachusetts | United States | 41.63 | -70.39 | 19 | |
| Otis | city | Massachusetts | United States | 42.19 | -73.09 | 1233 | |
| Otis Wood Lanes | city | Massachusetts | United States | 42.19 | -73.10 | 1669 | |
| Otter River | city | Massachusetts | United States | 42.60 | -72.05 | 905 | |
| Overbrook | city | Massachusetts | United States | 42.31 | -71.32 | 147 | |
| Owen District | city | Massachusetts | United States | 42.16 | -72.69 | 396 | |
| Oxford | city | Massachusetts | United States | 42.12 | -71.86 | 830 | |
| Oxford | city | Massachusetts | United States | 41.66 | -70.91 | 49 | |
| Oxford Heights | city | Massachusetts | United States | 42.17 | -71.88 | 830 | |
| Oyster Harbors | city | Massachusetts | United States | 41.62 | -70.42 | 13 |