| Name | Gender | Pronounced | Usage | Popularity |
|---|---|---|---|---|
| Osip | O-seep | Russian | ||
| Osiris | o-SIE-ris (English) | Egyptian Mythology (Hellenized) | ||
| Oskar | AWS-kahr (German, Polish) | Swedish, Norwegian, Danish, German, Polish | ||
| Oskars | - | Latvian | ||
| Osmund | - | Anglo-Saxon | ||
| Osvald | - | Swedish, Norwegian, Danish | ||
| Osvaldo | - | Spanish, Italian, Portuguese | ||
| Oswald | AHZ-wawld (English), AWS-vahlt (German) | English, German, Anglo-Saxon | ||
| Oswine | - | Anglo-Saxon | ||
| OszkÁR | - | Hungarian | ||
| OtÁVia | - | Portuguese (Brazilian) | ||
| OtÁVio | - | Portuguese (Brazilian) | ||
| Otar | - | Georgian | ||
| Otgonbayar | - | Mongolian | ||
| Othmar | - | German, Czech, Ancient Germanic |