| Name | What | Region | Country | Lat | Long | Elev ft. | Pop est |
|---|---|---|---|---|---|---|---|
| O'Brien's Bridge | city | Clare | Ireland | 52.95 | -9.35 | 36 | 2287 |
| O'Briensbridge | city | Clare | Ireland | 52.75 | -8.50 | 150 | 4186 |
| O'Callaghansmills | city | Clare | Ireland | 52.84 | -8.69 | 190 | 1424 |
| Oatfield | city | Clare | Ireland | 52.76 | -8.68 | 830 | 1978 |
| Ogonnelloe | city | Clare | Ireland | 52.89 | -8.46 | 288 | 845 |
| Oil Mill Bridge | city | Clare | Ireland | 52.73 | -8.77 | 177 | 3914 |
| Oldtown | city | Clare | Ireland | 52.63 | -9.75 | 252 | 453 |
| Oughtdarra | city | Clare | Ireland | 53.06 | -9.35 | 232 | 720 |
| Oughterard | city | Clare | Ireland | 52.60 | -9.82 | 3 | 344 |
| Oughtmama | city | Clare | Ireland | 53.12 | -9.04 | 830 | 933 |
| O’Briensbridge | city | Clare | Ireland | 52.75 | -8.50 | 150 | 4186 |
| O’Brien’s Bridge | city | Clare | Ireland | 52.95 | -9.35 | 36 | 2287 |
| O’Callaghansmills | city | Clare | Ireland | 52.84 | -8.69 | 190 | 1424 |