| Name | Gender | Pronounced | Usage | Popularity |
|---|---|---|---|---|
| Otakar | - | Czech | ||
| Othmar | - | German, Czech, Ancient Germanic | ||
| Othniel | AWTH-nee-əl (English) | Biblical | ||
| Otho | - | Ancient Roman | ||
| Otieno | - | Eastern African, Luo | ||
| Otmar | - | German, Ancient Germanic | ||
| Otokar | - | Czech | ||
| OttÓ | - | Hungarian, Icelandic | ||
| Otto | AW-to (German), AH-to (English), OT-to (Finnish) | German, Swedish, Norwegian, Danish, Dutch, English, Finnish, Ancient Germanic | ||
| Ourbanos | - | Biblical Greek | ||
| Ouri | - | Biblical Greek | ||
| Ourias | - | Biblical Greek | ||
| Oved | - | Hebrew, Biblical Hebrew | ||
| Ovidius | - | Ancient Roman | ||
| Owain | O-wien (Welsh, Welsh Mythology) | Welsh, Welsh Mythology, Arthurian Romance |