| Name | Gender | Pronounced | Usage | Popularity |
|---|---|---|---|---|
| Olaf | O-lahf (German, Dutch) | Norwegian, Danish, German, Dutch, Polish | ||
| Olivier | o-lee-VYE (French), O-lee-veer (Dutch) | French, Dutch | ||
| Oscar | AHS-kər (English) | English, Irish, Portuguese (Brazilian), Italian, Swedish, Norwegian, Danish, Dutch, French, Irish My | ||
| Otto | AW-to (German), AH-to (English), OT-to (Finnish) | German, Swedish, Norwegian, Danish, Dutch, English, Finnish, Ancient Germanic |