| Name | Gender | Pronounced | Usage | Popularity |
|---|---|---|---|---|
| Onyeka | - | Western African, Igbo | ||
| Onyekachi | - | Western African, Igbo | ||
| Onyekachukwu | - | Western African, Igbo | ||
| Opeyemi | - | Western African, Yoruba | ||
| Orabela | o-rah-BE-lah | Esperanto | ||
| Orazio | - | Italian | ||
| OrbÁN | - | Hungarian | ||
| Orfeo | - | Italian, Spanish | ||
| Oria | - | Italian | ||
| Oriana | o-RYAH-nah | Italian | ||
| Origenes | - | Ancient Greek | ||
| Oriol | - | Catalan | ||
| Orla (2) | - | Danish | ||
| Orlanda | or-LAHN-dah | Italian | ||
| Orlando | or-LAHN-do | Italian |