| Name | What | Region | Country | Lat | Long | Elev ft. | Pop est |
|---|---|---|---|---|---|---|---|
| Όαση | city | Dytiki Ellada | Greece | 38.08 | 22.34 | 2063 | 2468 |
| Όαση | city | Kriti | Greece | 35.48 | 23.96 | 75 | 20557 |
| Όαση | city | Peloponnisos | Greece | 38.00 | 22.95 | 0 | 6696 |
| Όασις | city | Dytiki Ellada | Greece | 38.08 | 22.34 | 2063 | 2468 |
| Όασις | city | Peloponnisos | Greece | 38.00 | 22.95 | 0 | 6696 |
| Όθος | city | Notio Aigaio | Greece | 35.53 | 27.15 | 1669 | 2831 |
| Όλβιο | city | Anatoliki Makedonia kai Thraki | Greece | 41.03 | 24.80 | 49 | 3428 |
| Όλβιον | city | Anatoliki Makedonia kai Thraki | Greece | 41.03 | 24.80 | 49 | 3428 |
| Όλγα | city | Dytiki Ellada | Greece | 37.90 | 21.35 | 75 | 6893 |
| Όλυμπος | city | Attiki | Greece | 37.78 | 23.95 | 830 | 16054 |
| Όλυμπος | city | Notio Aigaio | Greece | 35.74 | 27.17 | 830 | 321 |
| Όλυνθος | city | Kentriki Makedonia | Greece | 40.29 | 23.34 | 36 | 7732 |
| Όνειρο | city | Peloponnisos | Greece | 37.93 | 23.03 | 95 | 9341 |
| Όριο | city | Sterea Ellada | Greece | 38.53 | 24.12 | 150 | 3463 |
| Όριον | city | Sterea Ellada | Greece | 38.53 | 24.12 | 150 | 3463 |
| Όρμα | city | Kentriki Makedonia | Greece | 40.95 | 21.93 | 1046 | 2129 |
| Όρμη | city | Kentriki Makedonia | Greece | 40.95 | 21.93 | 1046 | 2129 |
| Όρμος Αγίου Ισιδώρου | city | Voreio Aigaio | Greece | 37.75 | 26.59 | 219 | 1265 |
| Όρμος Αιγιάλης | city | Notio Aigaio | Greece | 36.90 | 25.98 | 1669 | 538 |
| Όρμος Κορθίου | city | Notio Aigaio | Greece | 37.77 | 24.95 | 3 | 2350 |
| Όρμος Κουμαιίκων | city | Voreio Aigaio | Greece | 37.70 | 26.75 | 0 | 1854 |
| Όρμος Μαραθοκάμπου | city | Voreio Aigaio | Greece | 37.71 | 26.70 | 0 | 3285 |
| Όρμος Πάχη | city | Attiki | Greece | 37.97 | 23.36 | 0 | 7639 |
| Όρμος Πρίνου | city | Anatoliki Makedonia kai Thraki | Greece | 40.76 | 24.58 | 19 | 1557 |
| Όροβνικ | city | Dytiki Makedonia | Greece | 40.76 | 21.15 | 3349 | 446 |
| Όρος | city | Kriti | Greece | 35.29 | 24.50 | 1669 | 17127 |
| Όσσα | city | Kentriki Makedonia | Greece | 40.84 | 23.21 | 1866 | 1052 |
| Όσσα | city | Thessalia | Greece | 39.75 | 22.58 | 830 | 3059 |
| Όσσιανη | city | Dytiki Makedonia | Greece | 40.52 | 21.08 | 2509 | 1862 |
| Όσσιανη | city | Kentriki Makedonia | Greece | 41.08 | 22.28 | 3349 | 1942 |
| Όστιμα | city | Dytiki Makedonia | Greece | 40.74 | 21.20 | 3441 | 433 |
| Όστροβο | city | Kentriki Makedonia | Greece | 40.80 | 21.84 | 2001 | 2266 |
| Όχθια | city | Dytiki Ellada | Greece | 38.66 | 21.28 | 127 | 5717 |
| Όχθια | city | Peloponnisos | Greece | 37.66 | 21.90 | 2509 | 1525 |
| Όχτια | city | Sterea Ellada | Greece | 39.03 | 21.45 | 1669 | 895 |
| Όχτος | city | Peloponnisos | Greece | 37.05 | 22.90 | 2582 | 688 |