| Name | What | Region | Country | Lat | Long | Elev Ft. | Pop Est |
| Ochunak | city | Ostan-e Tehran | Iran | 35.5605556 | 52.2338889 | 6414 | 47859 |
| Ochūnak | city | Ostan-e Tehran | Iran | 35.5605556 | 52.2338889 | 6414 | 47859 |
| Onasirabad | city | Ostan-e Tehran | Iran | 35.3305556 | 51.5736111 | 2887 | 48122 |
| Onaşīrābād | city | Ostan-e Tehran | Iran | 35.3305556 | 51.5736111 | 2887 | 48122 |
| Ondariyeh | city | Ostan-e Tehran | Iran | 35.7855556 | 52.4552778 | 6883 | 47849 |
| Ondarīyeh | city | Ostan-e Tehran | Iran | 35.7855556 | 52.4552778 | 6883 | 47849 |
| Oojoonak | city | Ostan-e Tehran | Iran | 35.5605556 | 52.2338889 | 6414 | 47859 |
| Orin | city | Ostan-e Tehran | Iran | 35.5469444 | 51.1266667 | 3471 | 47972 |
| Orīn | city | Ostan-e Tehran | Iran | 35.5469444 | 51.1266667 | 3471 | 47972 |
| Oshtorak | city | Ostan-e Tehran | Iran | 36.05 | 51.3166667 | 7112 | 47671 |
| Oskul Deh | city | Ostan-e Tehran | Iran | 36.0333333 | 50.8333333 | 6341 | 47698 |
| Oskūl Deh | city | Ostan-e Tehran | Iran | 36.0333333 | 50.8333333 | 6341 | 47698 |
| Osun | city | Ostan-e Tehran | Iran | 35.85 | 51.4166667 | 6758 | 47797 |
| Osūn | city | Ostan-e Tehran | Iran | 35.85 | 51.4166667 | 6758 | 47797 |
| Ovreh | city | Ostan-e Tehran | Iran | 35.7363889 | 52.0655556 | 6496 | 46515 |
| Ovrin | city | Ostan-e Tehran | Iran | 35.5469444 | 51.1266667 | 3471 | 47972 |
| Ovrīn | city | Ostan-e Tehran | Iran | 35.5469444 | 51.1266667 | 3471 | 47972 |
| Owchunak | city | Ostan-e Tehran | Iran | 35.5605556 | 52.2338889 | 6414 | 47859 |
| Owchūnak | city | Ostan-e Tehran | Iran | 35.5605556 | 52.2338889 | 6414 | 47859 |
| Owlia' | city | Ostan-e Tehran | Iran | 35.19 | 51.7475 | 2696 | 48196 |
| Owlīā' | city | Ostan-e Tehran | Iran | 35.19 | 51.7475 | 2696 | 48196 |
| Ozbaki | city | Ostan-e Tehran | Iran | 35.9911111 | 50.5433333 | 3825 | 34529 |
| Ozbakī | city | Ostan-e Tehran | Iran | 35.9911111 | 50.5433333 | 3825 | 34529 |
| Ozgol | city | Ostan-e Tehran | Iran | 35.795 | 51.4983333 | 5118 | 47824 |
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