| Name | Gender | Pronounced | Usage | Popularity |
|---|---|---|---|---|
| Oswine | - | Anglo-Saxon | ||
| OszkÁR | - | Hungarian | ||
| OtÁVia | - | Portuguese (Brazilian) | ||
| OtÁVio | - | Portuguese (Brazilian) | ||
| Otar | - | Georgian | ||
| Otgonbayar | - | Mongolian | ||
| Othmar | - | German, Czech, Ancient Germanic | ||
| Otho | - | Ancient Roman | ||
| Otieno | - | Eastern African, Luo | ||
| Otmar | - | German, Ancient Germanic | ||
| OttÓ | - | Hungarian, Icelandic | ||
| Ottavia | - | Italian | ||
| Ottaviano | - | Italian | ||
| Ottavio | - | Italian | ||
| Ottilie | o-TEE-lee-ə | German |