男士名:
| Name | Meaning | Origin | Gender |
| OCTAVIO | The Eighth | Latin | M |
| OCTAVIOUS | Eighth | Latin | M |
| OCTAVIUS | The Eighth | Greek | M |
| ODED | Strong | Hebrew | M |
| ODYSSEUS | Full of Wrath | Greek | M |
| OGDEN | From the Valley of Oaks | English | M |
| OLAF | Ancestor | Scandinavian | M |
| OLEG | Sacred | Slavic | M |
| OLIVER | Olive Tree- Peace | Latin | M |
| OLLIE | From the name OLIVER | Greek | M |
| OMA | Commander | Arabic | M |
| OMAR | Ultimate Devotee | Arabic | M |
| ON | Peace | Chinese | M |
| ONAN | Wealthy | Turkish | M |
| ONOFRE | Defender of Peace | Spanish | M |
| ONSLOW | Hill of the Passionate One | Arabic | M |
| ORAL | Speaker, Word | Latin | M |
| OREN | A Tree | Hebrew | M |
| ORESTES | Mountain Man | Greek | M |
| ORINGO | He Who Likes the Hunt | African | M |
| ORLANDO | Land of Gold | Spanish | M |
| ORMAND | Serpent | German | M |
| ORNICE | Cedar Tree | Hebrew | M |
| ORO | Gold | Spanish | M |
| ORRICK | Venerable Oak | English | M |
| ORRIN | River | English | M |
| ORSEN | From the name ORSON | Latin | M |
| ORSIN | Bear | Latin | M |
| ORSON | A Bear | Latin | M |
| ORVILLE | Golden City | French | M |
| OSAMA | Lion-Like | Arabic | M |
| OSBORN | Bear of God | Scandinavian | M |
| OSBOURNE | Born from a Bear | Scandinavian | M |
| OSCAR | Accurate spearsman | Scandinavian | M |
| OSGOOD | Goth of the Heavens | English | M |
| OSIAS | Salvation | Greek | M |
| OSMAN | Tender Youth | Arabic | M |
| OSMOND | Godly Protector | English | M |
| OSRIC | Divine Ruler | English | M |
| OSSIE | God's Divine Power | English | M |
| OSWALD | God of the Forest | English | M |
| OTHELLO | Prosperous | Greek | M |
| OTIENO | Born at Night | African | M |
| OTIS | One Who Hears Well | Greek | M |
| OTTO | Wealthy | German | M |
| OVID | Egg Shaped | Latin | M |
| OVIDIO | Shepherd | Spanish | M |
| OWEN | Born to nobility | Celtic/Gaelic | M |
| OZZIE | God's Divine Power | English | M |
| OZZY | God's Divine Power | English | M |