| Name | What | Region | Country | Lat | Long | Elev ft. | Pop est |
|---|---|---|---|---|---|---|---|
| Odell Ville | city | Ireland | 52.46 | -8.89 | 380 | 1618 | |
| Old Bridge | city | Ireland | 52.58 | -8.33 | 213 | 3301 | |
| Old Kildimo | city | Ireland | 52.61 | -8.81 | 32 | 3154 | |
| Old Pallas | city | Ireland | 52.55 | -8.35 | 830 | 2582 | |
| Oldmill Bridge | city | Ireland | 52.48 | -9.10 | 347 | 4296 | |
| Oldtown | city | Ireland | 52.48 | -8.40 | 269 | 2544 | |
| Oola | city | Ireland | 52.53 | -8.26 | 311 | 2251 | |
| Oolagh Bridge | city | Ireland | 52.42 | -9.27 | 830 | 3350 | |
| Ospidéal Ghleann Áine | city | Ireland | 52.47 | -8.43 | 255 | 2721 |