| Name | Gender | Pronounced | Usage | Popularity |
|---|---|---|---|---|
| Nomiki | - | Greek | ||
| Nymphodora | - | Ancient Greek | ||
| Nyx | - | Greek Mythology | ||
| Obed | O-bed (English) | Biblical, Biblical Latin, Biblical Greek | ||
| Oceanus | - | Greek Mythology (Latinized) | ||
| Odysseus | o-DIS-ee-əs (English) | Greek Mythology | ||
| Oedipus | ED-i-pəs (English), EED-i-pəs (English) | Greek Mythology (Latinized) | ||
| Oenone | - | Greek Mythology (Latinized) | ||
| Oidipous | - | Greek Mythology | ||
| Oinone | - | Greek Mythology | ||
| Okeanos | - | Greek Mythology | ||
| Olympia | - | Greek, Slovak | ||
| Olympias | - | Ancient Greek | ||
| Olympiodoros | - | Ancient Greek | ||
| Olympos | - | Ancient Greek |