| Name | Gender | Pronounced | Usage | Popularity |
|---|---|---|---|---|
| Olympia | - | Greek, Slovak | ||
| Olyvia | ə-LIV-ee-ə | English (Rare) | ||
| Omar (1) | - | Arabic, English | ||
| Omega | o-MAY-gə (English) | Various | ||
| Omid | - | Persian | ||
| Omobolanle | - | Western African, Yoruba | ||
| Omolara | - | Western African, Yoruba | ||
| OnÓRa | - | Irish | ||
| Ondina | - | Portuguese, Italian | ||
| Ondrej | - | Slovak | ||
| Oneida | o-NIE-də | English | ||
| Oni | - | Western African, Yoruba | ||
| Onisim | - | Russian (Rare) | ||
| Onisimu | - | Old Church Slavic | ||
| Onni | ON-nee | Finnish |