| Name | What | Region | Country | Lat | Long | Elev ft. | Pop est |
|---|---|---|---|---|---|---|---|
| Oba | city | Euskadi | Spain | 43.14 | -2.72 | 2027 | 12918 |
| Obecuri | city | Euskadi | Spain | 43.28 | -3.15 | 213 | 11175 |
| Obekolaldea | city | Euskadi | Spain | 43.31 | -2.46 | 830 | 13981 |
| Ocamica | city | Euskadi | Spain | 43.33 | -2.53 | 830 | 9691 |
| Ocerinmendi | city | Euskadi | Spain | 43.10 | -2.75 | 1023 | 2592 |
| Ocerinmendio | city | Euskadi | Spain | 43.10 | -2.75 | 1023 | 2592 |
| Ochandiano | city | Euskadi | Spain | 43.04 | -2.65 | 1837 | 2317 |
| Ocio | city | Euskadi | Spain | 42.66 | -2.82 | 1706 | 2350 |
| Ocola | city | Euskadi | Spain | 43.31 | -2.46 | 830 | 13981 |
| Ocáriz | city | Euskadi | Spain | 42.84 | -2.36 | 2509 | 3619 |
| Odiaga | city | Euskadi | Spain | 43.32 | -2.52 | 830 | 9599 |
| Ogaragoitia | city | Euskadi | Spain | 43.12 | -2.75 | 1669 | 3689 |
| Oiardo | city | Euskadi | Spain | 42.99 | -2.93 | 2509 | 2842 |
| Oikia | city | Euskadi | Spain | 43.28 | -2.23 | 347 | 21396 |
| Oion / Oyón | city | Euskadi | Spain | 42.51 | -2.44 | 1669 | 52159 |
| Oiquina | city | Euskadi | Spain | 43.28 | -2.23 | 347 | 21396 |
| Okamika | city | Euskadi | Spain | 43.33 | -2.53 | 830 | 9691 |
| Okariz | city | Euskadi | Spain | 42.84 | -2.36 | 2509 | 3619 |
| Okina | city | Euskadi | Spain | 42.76 | -2.59 | 3349 | 6306 |
| Okoizta | city | Euskadi | Spain | 42.97 | -2.71 | 2076 | 1276 |
| Okoizta / Acosta | city | Euskadi | Spain | 42.97 | -2.71 | 2076 | 1276 |
| Olabarri | city | Euskadi | Spain | 43.16 | -2.78 | 403 | 8996 |
| Olabarri / Ollávarre | city | Euskadi | Spain | 42.82 | -2.84 | 1669 | 3728 |
| Olabarrieta | city | Euskadi | Spain | 43.03 | -2.39 | 1076 | 13885 |
| Olabarrieta / Labarrieta | city | Euskadi | Spain | 43.26 | -3.19 | 1669 | 6001 |
| Olabarrietagoikoa | city | Euskadi | Spain | 43.26 | -3.20 | 830 | 5165 |
| Olabarrietagoikoa / Las Barrietas Altas | city | Euskadi | Spain | 43.26 | -3.20 | 830 | 5165 |
| Olabazar | city | Euskadi | Spain | 43.07 | -3.01 | 830 | 6979 |
| Olabe | city | Euskadi | Spain | 43.37 | -2.58 | 830 | 1919 |
| Olaberría | city | Euskadi | Spain | 43.03 | -2.20 | 935 | 27202 |
| Olabezahar | city | Euskadi | Spain | 43.07 | -3.01 | 830 | 6979 |
| Olabezar | city | Euskadi | Spain | 43.07 | -3.01 | 830 | 6979 |
| Olacueta | city | Euskadi | Spain | 43.17 | -2.58 | 846 | 24617 |
| Olaeta | city | Euskadi | Spain | 43.05 | -2.63 | 2093 | 2319 |
| Olagorta | city | Euskadi | Spain | 43.37 | -2.61 | 377 | 3045 |
| Olakueta | city | Euskadi | Spain | 43.17 | -2.58 | 846 | 24617 |
| Olano | city | Euskadi | Spain | 43.06 | -2.10 | 830 | 5916 |
| Olarra | city | Euskadi | Spain | 43.15 | -2.79 | 830 | 7257 |
| Olavarri | city | Euskadi | Spain | 43.16 | -2.78 | 403 | 8996 |
| Olave | city | Euskadi | Spain | 43.17 | -2.57 | 830 | 21732 |
| Olazabal | city | Euskadi | Spain | 43.11 | -2.60 | 905 | 15298 |
| Olazábal | city | Euskadi | Spain | 43.14 | -2.76 | 830 | 6058 |
| Ollávarre | city | Euskadi | Spain | 42.82 | -2.84 | 1669 | 3728 |
| Ollávarre/Olabarri | city | Euskadi | Spain | 42.82 | -2.84 | 1669 | 3728 |
| Olquina | city | Euskadi | Spain | 43.28 | -2.23 | 347 | 21396 |
| Oma | city | Euskadi | Spain | 43.34 | -2.62 | 830 | 3774 |
| Onarte | city | Euskadi | Spain | 43.30 | -2.76 | 830 | 7714 |
| Ondarra | city | Euskadi | Spain | 42.98 | -2.29 | 1669 | 3583 |
| Ondarraldea | city | Euskadi | Spain | 42.98 | -2.29 | 1669 | 3583 |
| Ondategi | city | Euskadi | Spain | 42.96 | -2.74 | 1958 | 4726 |
| Ondategui | city | Euskadi | Spain | 42.96 | -2.74 | 1958 | 4726 |
| Ondárroa | city | Euskadi | Spain | 43.33 | -2.42 | 52 | 14110 |
| Onraita | city | Euskadi | Spain | 42.80 | -2.40 | 3349 | 2911 |
| Onraita/Erroeta | city | Euskadi | Spain | 42.80 | -2.40 | 3349 | 2911 |
| Opacua | city | Euskadi | Spain | 42.83 | -2.36 | 2690 | 3741 |
| Opakua | city | Euskadi | Spain | 42.83 | -2.36 | 2690 | 3741 |
| Opellora | city | Euskadi | Spain | 43.10 | -3.10 | 830 | 1919 |
| Opellora / Costera | city | Euskadi | Spain | 43.10 | -3.10 | 830 | 1919 |
| Oquina | city | Euskadi | Spain | 42.76 | -2.59 | 3349 | 6306 |
| Orbiso | city | Euskadi | Spain | 42.70 | -2.34 | 1817 | 1059 |
| Orconera | city | Euskadi | Spain | 43.30 | -3.06 | 879 | 190344 |
| Ordizia | city | Euskadi | Spain | 43.05 | -2.17 | 830 | 25554 |
| Ordonana | city | Euskadi | Spain | 42.87 | -2.38 | 1935 | 3807 |
| Ordorica | city | Euskadi | Spain | 43.27 | -2.68 | 354 | 19339 |
| Ordorika | city | Euskadi | Spain | 43.27 | -2.68 | 354 | 19339 |
| Orduna | city | Euskadi | Spain | 42.99 | -3.01 | 921 | 8217 |
| Orduña-Urduña | city | Euskadi | Spain | 42.99 | -3.01 | 921 | 8217 |
| Oreitia | city | Euskadi | Spain | 42.86 | -2.56 | 1771 | 30884 |
| Oreja | city | Euskadi | Spain | 43.09 | -2.01 | 1669 | 3782 |
| Orendain | city | Euskadi | Spain | 43.08 | -2.11 | 1040 | 15679 |
| Orenin | city | Euskadi | Spain | 42.90 | -2.55 | 1742 | 11565 |
| Orereta | city | Euskadi | Spain | 43.31 | -1.90 | 95 | 94174 |
| Orexa | city | Euskadi | Spain | 43.09 | -2.01 | 1669 | 3782 |
| Oria | city | Euskadi | Spain | 43.26 | -2.02 | 370 | 105314 |
| Orio | city | Euskadi | Spain | 43.28 | -2.13 | 183 | 28356 |
| Ormaiztegi | city | Euskadi | Spain | 43.04 | -2.26 | 830 | 13662 |
| Ormaiztegui | city | Euskadi | Spain | 43.04 | -2.26 | 830 | 13662 |
| Ormijana | city | Euskadi | Spain | 42.83 | -2.93 | 1876 | 178 |
| Oro | city | Euskadi | Spain | 43.04 | -2.49 | 1122 | 31094 |
| Orobio | city | Euskadi | Spain | 43.20 | -2.66 | 1128 | 33494 |
| Oromiño | city | Euskadi | Spain | 43.20 | -2.66 | 1128 | 33494 |
| Orozketa | city | Euskadi | Spain | 43.17 | -2.67 | 830 | 38030 |
| Ortuella | city | Euskadi | Spain | 43.31 | -3.05 | 180 | 192565 |
| Ortuzar | city | Euskadi | Spain | 43.15 | -2.65 | 892 | 35387 |
| Orózqueta | city | Euskadi | Spain | 43.17 | -2.67 | 830 | 38030 |
| Osintxu | city | Euskadi | Spain | 43.16 | -2.40 | 951 | 22447 |
| Osma | city | Euskadi | Spain | 42.89 | -3.06 | 2509 | 282 |
| Osma | city | Euskadi | Spain | 43.20 | -2.55 | 941 | 23263 |
| Otazu | city | Euskadi | Spain | 42.83 | -2.63 | 1765 | 69241 |
| Otceremendi | city | Euskadi | Spain | 43.10 | -2.75 | 1023 | 2592 |
| Oteo | city | Euskadi | Spain | 42.72 | -2.37 | 2509 | 948 |
| Otides | city | Euskadi | Spain | 43.23 | -3.38 | 830 | 2282 |
| Oto Barren | city | Euskadi | Spain | 42.89 | -2.80 | 1689 | 19035 |
| Oto Goien | city | Euskadi | Spain | 42.89 | -2.80 | 1732 | 19035 |
| Oto Goien / Hueto Arriba | city | Euskadi | Spain | 42.89 | -2.80 | 1732 | 19035 |
| Otobarren | city | Euskadi | Spain | 42.89 | -2.80 | 1689 | 19035 |
| Otobarren / Hueto Abajo | city | Euskadi | Spain | 42.89 | -2.80 | 1689 | 19035 |
| Otogoien | city | Euskadi | Spain | 42.89 | -2.80 | 1732 | 19035 |
| Otogoien / Hueto Arriba | city | Euskadi | Spain | 42.89 | -2.80 | 1732 | 19035 |
| Otsaurte | city | Euskadi | Spain | 42.93 | -2.25 | 2080 | 4365 |
| Otxandio | city | Euskadi | Spain | 43.04 | -2.65 | 1837 | 2317 |
| Otzaurte | city | Euskadi | Spain | 42.93 | -2.25 | 2080 | 4365 |
| Otzerinmendi | city | Euskadi | Spain | 43.10 | -2.75 | 1023 | 2592 |
| Oyardo | city | Euskadi | Spain | 42.99 | -2.93 | 2509 | 2842 |
| Oyon | city | Euskadi | Spain | 42.51 | -2.44 | 1669 | 52159 |
| Oyón/Oion | city | Euskadi | Spain | 42.51 | -2.44 | 1669 | 52159 |
| Ozaeta | city | Euskadi | Spain | 42.92 | -2.49 | 1814 | 640 |
| Oñate | city | Euskadi | Spain | 43.03 | -2.41 | 938 | 12971 |
| Oñati | city | Euskadi | Spain | 43.03 | -2.41 | 938 | 12971 |
| Oñatz | city | Euskadi | Spain | 43.16 | -2.26 | 830 | 17339 |