| Name | What | Region | Country | Lat | Long | Elev ft. | Pop est |
|---|---|---|---|---|---|---|---|
| Οία | city | Notio Aigaio | Greece | 36.46 | 25.38 | 830 | 2041 |
| Οίον | city | Attiki | Greece | 38.13 | 23.86 | 1669 | 71268 |
| Οίτη | city | Sterea Ellada | Greece | 38.74 | 22.40 | 1817 | 781 |
| Οίτυλο | city | Peloponnisos | Greece | 36.71 | 22.39 | 121 | 1515 |
| Οίτυλον | city | Peloponnisos | Greece | 36.71 | 22.39 | 121 | 1515 |
| Οβριά | city | Dytiki Ellada | Greece | 38.19 | 21.73 | 252 | 61128 |
| Οβρυά | city | Dytiki Ellada | Greece | 38.19 | 21.73 | 252 | 61128 |
| Οδηγήτρια | city | Kentriki Makedonia | Greece | 41.23 | 23.01 | 830 | 2892 |
| Οζιάς | city | Ionia Nisia | Greece | 39.19 | 20.19 | 0 | 1699 |
| Οθωμανικό | city | Thessalia | Greece | 39.25 | 22.19 | 830 | 1776 |
| Οθωμανικόν | city | Thessalia | Greece | 39.25 | 22.19 | 830 | 1776 |
| Οθωνοί | city | Ionia Nisia | Greece | 39.84 | 19.40 | 0 | 328 |
| Οικισμός | city | Attiki | Greece | 38.15 | 23.86 | 1099 | 50794 |
| Οικισμός Ανθέων | city | Attiki | Greece | 38.28 | 23.91 | 830 | 3920 |
| Οικισμός Λαχνών | city | Attiki | Greece | 38.30 | 23.81 | 830 | 9387 |
| Οικισμός Παπάγου | city | Attiki | Greece | 37.99 | 23.79 | 862 | 766923 |
| Οικισμός Ποντίων | city | Attiki | Greece | 38.15 | 23.86 | 1099 | 50794 |
| Οικονομαίικα | city | Dytiki Ellada | Greece | 38.15 | 22.37 | 3 | 4117 |
| Οικονομιάνικα | city | Peloponnisos | Greece | 36.52 | 23.05 | 0 | 3771 |
| Οινοχώρι | city | Sterea Ellada | Greece | 38.70 | 22.36 | 2509 | 1074 |
| Οινοχώριον | city | Sterea Ellada | Greece | 38.70 | 22.36 | 2509 | 1074 |
| Οινούσα | city | Kentriki Makedonia | Greece | 41.10 | 23.63 | 830 | 18374 |
| Οινούσσα | city | Kentriki Makedonia | Greece | 41.10 | 23.63 | 830 | 18374 |
| Οινούσσαι | city | Voreio Aigaio | Greece | 38.51 | 26.22 | 0 | 776 |
| Οινούσσες | city | Voreio Aigaio | Greece | 38.51 | 26.22 | 0 | 776 |
| Οινόη | city | Dytiki Makedonia | Greece | 40.32 | 21.92 | 2532 | 5906 |
| Οινόη | city | Sterea Ellada | Greece | 38.32 | 23.61 | 416 | 14042 |
| Οινόη | city | Attiki | Greece | 38.17 | 23.42 | 951 | 2119 |
| Οινόη | city | Dytiki Ellada | Greece | 37.84 | 21.52 | 830 | 3745 |
| Οινόη | city | Dytiki Makedonia | Greece | 40.52 | 21.08 | 2509 | 1862 |
| Οινόφυτα | city | Sterea Ellada | Greece | 38.31 | 23.64 | 285 | 12648 |
| Οιχαλία | city | Peloponnisos | Greece | 37.25 | 22.00 | 311 | 4413 |
| Οιχαλία | city | Thessalia | Greece | 39.61 | 21.98 | 383 | 5547 |
| Οκτωνιά | city | Sterea Ellada | Greece | 38.53 | 24.16 | 1725 | 2549 |
| Ολυμπιάδα | city | Kentriki Makedonia | Greece | 40.59 | 23.78 | 0 | 533 |
| Ολυμπιάδα | city | Dytiki Makedonia | Greece | 40.57 | 21.60 | 2047 | 5041 |
| Ολυμπιάδα | city | Thessalia | Greece | 39.99 | 22.25 | 1811 | 1057 |
| Ολυμπιάς | city | Kentriki Makedonia | Greece | 40.59 | 23.78 | 0 | 533 |
| Ολυμπιάς | city | Dytiki Makedonia | Greece | 40.57 | 21.60 | 2047 | 5041 |
| Ολυμπιάς | city | Thessalia | Greece | 39.99 | 22.25 | 1811 | 1057 |
| Ολυμπιές | city | Peloponnisos | Greece | 36.52 | 22.46 | 1669 | 1218 |
| Ολυμπια | city | Dytiki Ellada | Greece | 37.65 | 21.63 | 167 | 9605 |
| Ολυμπιαί | city | Peloponnisos | Greece | 36.52 | 22.46 | 1669 | 1218 |
| Ολυμπιακή Ακτή | city | Kentriki Makedonia | Greece | 40.24 | 22.59 | 0 | 17104 |
| Ολύμποι | city | Voreio Aigaio | Greece | 38.25 | 25.94 | 830 | 1415 |
| Ομάλα | city | Kriti | Greece | 35.34 | 24.79 | 1669 | 4513 |
| Ομαλές | city | Peloponnisos | Greece | 36.66 | 22.38 | 396 | 1110 |
| Ομαλή | city | Dytiki Makedonia | Greece | 40.26 | 21.27 | 2670 | 1118 |
| Ομαλή | city | Ipeiros | Greece | 39.37 | 21.17 | 2811 | 1402 |
| Ομαλαί | city | Peloponnisos | Greece | 36.66 | 22.38 | 396 | 1110 |
| Ομαλό | city | Kentriki Makedonia | Greece | 40.91 | 22.40 | 1171 | 2536 |
| Ομαλόν | city | Kentriki Makedonia | Greece | 40.91 | 22.40 | 1171 | 2536 |
| Ομαλός | city | Kriti | Greece | 35.34 | 23.90 | 4189 | 543 |
| Ομβριακή | city | Sterea Ellada | Greece | 39.10 | 22.27 | 1738 | 3762 |
| Ομορφοκκλησιά | city | Dytiki Makedonia | Greece | 40.43 | 21.12 | 2913 | 1617 |
| Ομορφοχώρι | city | Thessalia | Greece | 39.68 | 22.48 | 232 | 43214 |
| Ομορφοχώριον | city | Thessalia | Greece | 39.68 | 22.48 | 232 | 43214 |
| Ομούρ-Βέη | city | Kentriki Makedonia | Greece | 40.85 | 23.68 | 830 | 1436 |
| Ομόλιο | city | Thessalia | Greece | 39.90 | 22.64 | 830 | 2904 |
| Ομόλιον | city | Thessalia | Greece | 39.90 | 22.64 | 830 | 2904 |
| Ονιθέ | city | Kriti | Greece | 35.27 | 24.50 | 1899 | 5319 |
| Οξυά | city | Dytiki Makedonia | Greece | 40.74 | 21.13 | 3349 | 423 |
| Οξυά | city | Dytiki Makedonia | Greece | 40.61 | 21.35 | 4281 | 504 |
| Οξυά | city | Ipeiros | Greece | 40.24 | 20.82 | 2890 | 393 |
| Οξυά | city | Thessalia | Greece | 39.36 | 21.60 | 2040 | 1495 |
| Οξύλιθος | city | Sterea Ellada | Greece | 38.58 | 24.11 | 396 | 3976 |
| Οξύνεια | city | Thessalia | Greece | 39.83 | 21.49 | 1669 | 1224 |
| Ορέβιστα | city | Kentriki Makedonia | Greece | 41.04 | 22.58 | 830 | 3323 |
| Ορέσκεια | city | Kentriki Makedonia | Greece | 40.86 | 23.64 | 370 | 1516 |
| Ορέστειο | city | Peloponnisos | Greece | 37.42 | 22.12 | 1246 | 3869 |
| Ορέστειον | city | Peloponnisos | Greece | 37.42 | 22.12 | 1246 | 3869 |
| Οραιόβιτσα | city | Kentriki Makedonia | Greece | 41.04 | 22.58 | 830 | 3323 |
| Οργάνη | city | Anatoliki Makedonia kai Thraki | Greece | 41.25 | 25.68 | 1922 | 1308 |
| Ορεβίτσα | city | Kentriki Makedonia | Greece | 41.04 | 22.58 | 830 | 3323 |
| Ορεινή | city | Kentriki Makedonia | Greece | 41.20 | 23.59 | 2083 | 9530 |
| Ορεινή | city | Dytiki Ellada | Greece | 37.87 | 21.85 | 3349 | 1233 |
| Ορεινή | city | Thessalia | Greece | 39.44 | 21.34 | 3349 | 227 |
| Ορεινή Μελιγού | city | Peloponnisos | Greece | 37.36 | 22.66 | 2772 | 1192 |
| Ορεινό | city | Ipeiros | Greece | 39.97 | 20.34 | 2050 | 345 |
| Ορεινό | city | Kriti | Greece | 35.08 | 25.91 | 2509 | 2383 |
| Ορεινό Κορακοβούνι | city | Peloponnisos | Greece | 37.30 | 22.76 | 1669 | 2229 |
| Ορεινόν | city | Ipeiros | Greece | 39.97 | 20.34 | 2050 | 345 |
| Ορεινόν | city | Kriti | Greece | 35.08 | 25.91 | 2509 | 2383 |
| Ορεινόν Κορακοβούνιον | city | Peloponnisos | Greece | 37.30 | 22.76 | 1669 | 2229 |
| Ορεστιάδα | city | Anatoliki Makedonia kai Thraki | Greece | 41.51 | 26.53 | 72 | 11967 |
| Ορεστιάς | city | Anatoliki Makedonia kai Thraki | Greece | 41.51 | 26.53 | 72 | 11967 |
| Ορεστινή | city | Anatoliki Makedonia kai Thraki | Greece | 41.23 | 24.82 | 1991 | 449 |
| Ορεόβιτσα | city | Kentriki Makedonia | Greece | 41.04 | 22.58 | 830 | 3323 |
| Ορθές | city | Kriti | Greece | 35.34 | 24.70 | 1669 | 3814 |
| Ορθοβούνι | city | Thessalia | Greece | 39.76 | 21.47 | 1879 | 1213 |
| Ορθοβούνιον | city | Thessalia | Greece | 39.76 | 21.47 | 1879 | 1213 |
| Ορθολίθι | city | Dytiki Ellada | Greece | 38.05 | 22.01 | 2565 | 1043 |
| Ορθολίθιον | city | Dytiki Ellada | Greece | 38.05 | 22.01 | 2565 | 1043 |
| Ορθονιές | city | Ionia Nisia | Greece | 37.85 | 20.69 | 1669 | 2290 |
| Ορθονιαί | city | Ionia Nisia | Greece | 37.85 | 20.69 | 1669 | 2290 |
| Ορθούνι | city | Kriti | Greece | 35.40 | 23.90 | 1761 | 2099 |
| Ορθούνιον | city | Kriti | Greece | 35.40 | 23.90 | 1761 | 2099 |
| Ορμάν | city | Dytiki Makedonia | Greece | 40.52 | 21.21 | 2509 | 12323 |
| Ορμένιο | city | Anatoliki Makedonia kai Thraki | Greece | 41.72 | 26.22 | 134 | 2266 |
| Ορμένιον | city | Anatoliki Makedonia kai Thraki | Greece | 41.72 | 26.22 | 134 | 2266 |
| Ορμύλια | city | Kentriki Makedonia | Greece | 40.29 | 23.54 | 55 | 3745 |
| Ορνέ | city | Kriti | Greece | 35.15 | 24.66 | 830 | 2179 |
| Οροβάς | city | Peloponnisos | Greece | 36.94 | 22.21 | 997 | 2936 |
| Οροπέδιο | city | Anatoliki Makedonia kai Thraki | Greece | 41.34 | 24.25 | 2063 | 2536 |
| Οροπέδιο | city | Dytiki Makedonia | Greece | 40.12 | 21.31 | 2509 | 1223 |
| Οροπέδιον | city | Anatoliki Makedonia kai Thraki | Greece | 41.34 | 24.25 | 2063 | 2536 |
| Οροπέδιον | city | Dytiki Makedonia | Greece | 40.12 | 21.31 | 2509 | 1223 |
| Ορφάνι | city | Anatoliki Makedonia kai Thraki | Greece | 40.78 | 23.95 | 232 | 1720 |
| Ορφάνιο | city | Anatoliki Makedonia kai Thraki | Greece | 40.78 | 23.95 | 232 | 1720 |
| Ορφανά | city | Thessalia | Greece | 39.40 | 22.22 | 396 | 1939 |
| Ορφανό | city | Anatoliki Makedonia kai Thraki | Greece | 40.98 | 24.79 | 42 | 4400 |
| Ορφανόν | city | Anatoliki Makedonia kai Thraki | Greece | 40.98 | 24.79 | 42 | 4400 |
| Ορχομενός | city | Sterea Ellada | Greece | 38.49 | 22.98 | 328 | 8029 |
| Ορχομενός | city | Peloponnisos | Greece | 37.72 | 22.32 | 2509 | 1833 |
| Οσμάν Καμήλα | city | Kentriki Makedonia | Greece | 41.02 | 23.48 | 95 | 11186 |
| Οσμάναγα | city | Peloponnisos | Greece | 37.00 | 21.68 | 331 | 3756 |
| Οσνίτσανη | city | Dytiki Makedonia | Greece | 40.36 | 21.16 | 3425 | 1940 |
| Οτζιάς | city | Notio Aigaio | Greece | 37.67 | 24.35 | 154 | 777 |
| Ουμπαγιά | city | Kentriki Makedonia | Greece | 41.25 | 23.28 | 88 | 6720 |
| Ουρανούπολη | city | Kentriki Makedonia | Greece | 40.33 | 23.98 | 0 | 1227 |
| Ουρανούπολις | city | Kentriki Makedonia | Greece | 40.33 | 23.98 | 0 | 1227 |
| Ουρανόπολη | city | Kentriki Makedonia | Greece | 40.33 | 23.98 | 0 | 1227 |
| Ουρανόπολις | city | Kentriki Makedonia | Greece | 40.33 | 23.98 | 0 | 1227 |
| Ουρανός | city | Thessalia | Greece | 39.62 | 21.64 | 830 | 2909 |
| Οφρύνιο | city | Anatoliki Makedonia kai Thraki | Greece | 40.80 | 23.92 | 377 | 1748 |
| Οχιά | city | Peloponnisos | Greece | 36.48 | 22.39 | 400 | 877 |
| Οχυρό | city | Anatoliki Makedonia kai Thraki | Greece | 41.30 | 23.85 | 1860 | 2065 |
| Οχυρόν | city | Anatoliki Makedonia kai Thraki | Greece | 41.30 | 23.85 | 1860 | 2065 |
| Οψιγιάς | city | Kriti | Greece | 35.23 | 24.66 | 2509 | 2058 |
| Ούγγρα | city | Sterea Ellada | Greece | 38.43 | 23.30 | 406 | 1042 |