| Name | Gender | Pronounced | Usage | Popularity |
|---|---|---|---|---|
| OŽBALT | - | Slovene | ||
| OŽBEJ | - | Slovene | ||
| Oakes | [əukəz] | |||
| Oakley | ['əukli] | |||
| OBADIAH | o-bə-DIE-ə (English) | Biblical | ||
| OBED | O-bed (English) | Biblical, Biblical Latin, Biblical Greek | ||
| OBERON | O-bər-ahn (English) | Literature | ||
| OBI | - | Western African, Igbo | ||
| OBRAD | - | Serbian | ||
| OCEANUS | - | Greek Mythology (Latinized) | ||
| OCHIENG | - | Eastern African, Luo | ||
| OCTÁVIO | - | Portuguese | ||
| OCTAVE | - | French | ||
| OCTAVIAN | ahk-TAYV-ee-ən (English) | History, Romanian | ||
| OCTAVIANUS | - | Ancient Roman |