| Name | What | Region | Country | Lat | Long | Elev ft. | Pop est |
|---|---|---|---|---|---|---|---|
| Oasi dei Due Mari | city | Sardegna | Italy | 39.13 | 9.51 | 127 | 2694 |
| Olbia | city | Sardegna | Italy | 40.92 | 9.52 | 0 | 9794 |
| Olbia Marittima | city | Sardegna | Italy | 40.92 | 9.52 | 0 | 9794 |
| Oliena | city | Sardegna | Italy | 40.27 | 9.40 | 1820 | 9942 |
| Ollasta Useddus | city | Sardegna | Italy | 39.79 | 8.86 | 918 | 3911 |
| Ollasta Useddus/Albagiara | city | Sardegna | Italy | 39.79 | 8.86 | 918 | 3911 |
| Ollastra | city | Sardegna | Italy | 39.95 | 8.73 | 193 | 5373 |
| Ollastra Simaxis | city | Sardegna | Italy | 39.95 | 8.73 | 193 | 5373 |
| Ollastra Usellus | city | Sardegna | Italy | 39.79 | 8.86 | 918 | 3911 |
| Ollolai | city | Sardegna | Italy | 40.18 | 9.18 | 2591 | 4726 |
| Ollollai | city | Sardegna | Italy | 40.18 | 9.18 | 2591 | 4726 |
| Ollollai/Ollolai | city | Sardegna | Italy | 40.18 | 9.18 | 2591 | 4726 |
| Olmedo | city | Sardegna | Italy | 40.65 | 8.38 | 219 | 12898 |
| Olzai | city | Sardegna | Italy | 40.18 | 9.15 | 2509 | 3822 |
| Olìa Speciosa | city | Sardegna | Italy | 39.28 | 9.53 | 209 | 2645 |
| Onani | city | Sardegna | Italy | 40.48 | 9.43 | 1669 | 1175 |
| Onanìe | city | Sardegna | Italy | 40.48 | 9.43 | 1669 | 1175 |
| Onanìe/Onanì | city | Sardegna | Italy | 40.48 | 9.43 | 1669 | 1175 |
| Onieri | city | Sardegna | Italy | 40.27 | 9.17 | 1909 | 2751 |
| Onieri/Oniferi | city | Sardegna | Italy | 40.27 | 9.17 | 1909 | 2751 |
| Onifai | city | Sardegna | Italy | 40.40 | 9.65 | 216 | 3609 |
| Oniferi | city | Sardegna | Italy | 40.27 | 9.17 | 1909 | 2751 |
| Oniài | city | Sardegna | Italy | 40.40 | 9.65 | 216 | 3609 |
| Oniài/Onifai | city | Sardegna | Italy | 40.40 | 9.65 | 216 | 3609 |
| Opera Arbuticci | city | Sardegna | Italy | 41.22 | 9.47 | 0 | 4895 |
| Opera Arouticci | city | Sardegna | Italy | 41.22 | 9.47 | 0 | 4895 |
| Opera di Poggio Rasu | city | Sardegna | Italy | 41.20 | 9.47 | 0 | 3552 |
| Opera di Poggio Rasu Superiore | city | Sardegna | Italy | 41.20 | 9.47 | 0 | 3552 |
| Orane/Orani | city | Sardegna | Italy | 40.25 | 9.18 | 2001 | 2791 |
| Orani | city | Sardegna | Italy | 40.25 | 9.18 | 2001 | 2791 |
| Orgosolo | city | Sardegna | Italy | 40.20 | 9.35 | 2509 | 2124 |
| Orgòsolo/Orgosolo | city | Sardegna | Italy | 40.20 | 9.35 | 2509 | 2124 |
| Oristano | city | Sardegna | Italy | 39.90 | 8.59 | 49 | 19366 |
| Oristanum | city | Sardegna | Italy | 39.90 | 8.59 | 49 | 19366 |
| Oristany | city | Sardegna | Italy | 39.90 | 8.59 | 49 | 19366 |
| Orosei | city | Sardegna | Italy | 40.38 | 9.70 | 29 | 3802 |
| Oroteddi | city | Sardegna | Italy | 40.30 | 9.12 | 1138 | 3249 |
| Oroteddi/Orotelli | city | Sardegna | Italy | 40.30 | 9.12 | 1138 | 3249 |
| Orotelli | city | Sardegna | Italy | 40.30 | 9.12 | 1138 | 3249 |
| Orroli | city | Sardegna | Italy | 39.69 | 9.25 | 1988 | 3051 |
| Ortacesus | city | Sardegna | Italy | 39.54 | 9.08 | 830 | 6714 |
| Orthullè | city | Sardegna | Italy | 40.10 | 9.50 | 1761 | 1009 |
| Orthullè/Urzulei | city | Sardegna | Italy | 40.10 | 9.50 | 1761 | 1009 |
| Orti su Loi | city | Sardegna | Italy | 39.13 | 9.01 | 3 | 20296 |
| Ortueri | city | Sardegna | Italy | 40.03 | 8.98 | 1870 | 2999 |
| Ortzai | city | Sardegna | Italy | 40.18 | 9.15 | 2509 | 3822 |
| Ortzai/Olzai | city | Sardegna | Italy | 40.18 | 9.15 | 2509 | 3822 |
| Orune | city | Sardegna | Italy | 40.40 | 9.37 | 1669 | 5305 |
| Oscheri | city | Sardegna | Italy | 40.72 | 9.10 | 830 | 1760 |
| Oscheri/Oschiri | city | Sardegna | Italy | 40.72 | 9.10 | 830 | 1760 |
| Oschiri | city | Sardegna | Italy | 40.72 | 9.10 | 830 | 1760 |
| Osidda | city | Sardegna | Italy | 40.52 | 9.22 | 1975 | 2029 |
| Osidde | city | Sardegna | Italy | 40.52 | 9.22 | 1975 | 2029 |
| Osidde/Osidda | city | Sardegna | Italy | 40.52 | 9.22 | 1975 | 2029 |
| Osilo | city | Sardegna | Italy | 40.75 | 8.67 | 2066 | 7741 |
| Osini | city | Sardegna | Italy | 39.83 | 9.49 | 1669 | 3153 |
| Ossi | city | Sardegna | Italy | 40.68 | 8.59 | 1669 | 16445 |
| Othieri | city | Sardegna | Italy | 40.58 | 9.00 | 1669 | 8341 |
| Othieri/Ozieri | city | Sardegna | Italy | 40.58 | 9.00 | 1669 | 8341 |
| Ottana | city | Sardegna | Italy | 40.23 | 9.03 | 830 | 4017 |
| Otzana | city | Sardegna | Italy | 40.23 | 9.03 | 830 | 4017 |
| Otzana/Ottana | city | Sardegna | Italy | 40.23 | 9.03 | 830 | 4017 |
| Ovodda | city | Sardegna | Italy | 40.10 | 9.15 | 2509 | 3802 |
| Ovolaccio | city | Sardegna | Italy | 40.02 | 9.22 | 3349 | 3971 |
| Ozieri | city | Sardegna | Italy | 40.58 | 9.00 | 1669 | 8341 |