| Name | What | Region | Country | Lat | Long | Elev ft. | Pop est |
|---|---|---|---|---|---|---|---|
| Óasi | city | Dytiki Ellada | Greece | 38.08 | 22.34 | 2063 | 2468 |
| Óasi | city | Kriti | Greece | 35.48 | 23.96 | 75 | 20557 |
| Óasis | city | Dytiki Ellada | Greece | 38.08 | 22.34 | 2063 | 2468 |
| Óchthia | city | Dytiki Ellada | Greece | 38.66 | 21.28 | 127 | 5717 |
| Óchtos | city | Peloponnisos | Greece | 37.05 | 22.90 | 2582 | 688 |
| Ókhthia | city | Peloponnisos | Greece | 37.66 | 21.90 | 2509 | 1525 |
| Ólena | city | Dytiki Ellada | Greece | 37.74 | 21.56 | 334 | 5173 |
| Ólga | city | Dytiki Ellada | Greece | 37.90 | 21.35 | 75 | 6893 |
| Ólinthos | city | Kentriki Makedonia | Greece | 40.28 | 23.35 | 0 | 6848 |
| Ólympos | city | Attiki | Greece | 37.78 | 23.95 | 830 | 16054 |
| Ólympos | city | Notio Aigaio | Greece | 35.74 | 27.17 | 830 | 321 |
| Ómbar | city | Kentriki Makedonia | Greece | 40.84 | 22.30 | 75 | 2737 |
| Órliakon | city | Kentriki Makedonia | Greece | 41.04 | 23.31 | 104 | 3854 |
| Órma | city | Kentriki Makedonia | Greece | 40.95 | 21.93 | 1046 | 2129 |
| Órmos | city | Voreio Aigaio | Greece | 37.80 | 26.71 | 328 | 7470 |
| Órmos Agíou Isidórou | city | Voreio Aigaio | Greece | 37.75 | 26.59 | 219 | 1265 |
| Órmos Koumaíïkon | city | Voreio Aigaio | Greece | 37.70 | 26.75 | 0 | 1854 |
| Órmos Marathokámpou | city | Voreio Aigaio | Greece | 37.71 | 26.70 | 0 | 3285 |
| Órmos Prínou | city | Anatoliki Makedonia kai Thraki | Greece | 40.76 | 24.58 | 19 | 1557 |
| Órmos Ágios Isídoros | city | Voreio Aigaio | Greece | 37.75 | 26.59 | 219 | 1265 |
| Órmos Épanomís | city | Kentriki Makedonia | Greece | 40.41 | 22.90 | 0 | 5476 |
| Óros | city | Kriti | Greece | 35.29 | 24.50 | 1669 | 17127 |
| Órovnik | city | Dytiki Makedonia | Greece | 40.76 | 21.15 | 3349 | 446 |
| Ósiani | city | Dytiki Makedonia | Greece | 40.52 | 21.08 | 2509 | 1862 |
| Ósliani | city | Kentriki Makedonia | Greece | 40.71 | 22.00 | 1916 | 1844 |
| Óssa | city | Thessalia | Greece | 39.75 | 22.58 | 830 | 3059 |
| Óstima | city | Dytiki Makedonia | Greece | 40.74 | 21.20 | 3441 | 433 |
| Óthos | city | Notio Aigaio | Greece | 35.53 | 27.15 | 1669 | 2831 |