| Name | Gender | Pronounced | Usage | Popularity |
|---|---|---|---|---|
| Olyvia | ə-LIV-ee-ə | English (Rare) | ||
| Omar (1) | - | Arabic, English | ||
| OnÉSime | - | French | ||
| Oneida | o-NIE-də | English | ||
| Onesimos | - | Ancient Greek, Biblical Greek | ||
| Onesiphoros | - | Ancient Greek, Biblical Greek | ||
| Onfroi | - | Medieval French | ||
| Opal | O-pəl | English | ||
| Opaline | O-pə-leen | English (Rare) | ||
| OphÉLie | o-fe-LEE | French | ||
| Ophelia | o-FEEL-yə (English) | English, Literature | ||
| Ora (1) | - | English | ||
| Oral | - | English (Rare) | ||
| Oralee | - | English (Rare) | ||
| Oralie | - | English (Rare) |