| Name | Gender | Pronounced | Usage | Popularity |
|---|---|---|---|---|
| Ognian | - | Bulgarian | ||
| Ognjan | - | Croatian, Serbian | ||
| Ognjen | - | Croatian, Serbian | ||
| Ognyan | - | Bulgarian | ||
| Ognyana | - | Bulgarian | ||
| Ohannes | - | Armenian | ||
| Okoro | - | Western African, Urhobo | ||
| Okropir | - | Georgian | ||
| Oksana | ahk-SAH-nah (Russian) | Ukrainian, Russian | ||
| OlÍVia | - | Portuguese, Slovak, Hungarian | ||
| Ola (1) | - | Norwegian, Swedish | ||
| Olabode | - | Western African, Yoruba | ||
| Olaf | O-lahf (German, Dutch) | Norwegian, Danish, German, Dutch, Polish | ||
| Olalla | o-LAH-yah | Spanish | ||
| Olamide | - | Western African, Yoruba |