| Name | Gender | Pronounced | Usage | Popularity |
|---|---|---|---|---|
| Oneida | o-NIE-də | English | ||
| Opal | O-pəl | English | ||
| Opaline | O-pə-leen | English (Rare) | ||
| Ophelia | o-FEEL-yə (English) | English, Literature | ||
| Ora (1) | - | English | ||
| Oral | - | English (Rare) | ||
| Oralee | - | English (Rare) | ||
| Oralie | - | English (Rare) | ||
| Orinda | - | English (Rare) | ||
| Ormond | AWR-mənd | English (Rare) | ||
| Ormonde | - | English (Rare) | ||
| Orpha | AWR-fə (English) | Biblical, English | ||
| Orrell | - | English (Rare) | ||
| Orson | AWR-sən | English | ||
| Orval | AWR-vəl | English |