| Name | Meaning | Gender | Origin |
|---|
| Obiareus | Myth Name (A Titan) | Male | Greek |
| Oceanus | Myth Name (Father Of The Oceanids) | Male | Greek |
| Ocnus | Incompetent | Male | Greek |
| Odysseus | Wrathful | Male | Greek |
| Oedipus | Swollen Foot | Male | Greek |
| Oeneus | Myth Name (King Of Calydon) | Male | Greek |
| Oengus | One Vigor | Male | Irish |
| Oenomaus | Myth Name (Son Of Ares) | Male | Greek |
| Omusa | Miwok Name Meaning " Misses With Arrows." | Female | Native American |
| Ondrus | Manly | Male | Czechoslovakian |
| Orguelleuse | An Arrogant Lady | Female | Arthurian |
| Orpheus | Myth Name (Son Of Apollo) | Male | Greek |
| Pancratius | Supreme Ruler | Male | Greek |
| Pandarus | Myth Name (Killed For Breaking A Truce) | Male | Greek |
| Patroclus | Myth Name (Achilles' Best Friend) | Male | Greek |
| Pegasus | Myth Name (Winged Horse) | Male | Greek |
| Peisistratus | Myth Name (Son Of Nestor) | Male | Greek |
| Peleus | Myth Name (Father Of Achilles) | Male | Greek |
| Peneus | Myth Name | Male | Greek |
| Pentheus | Myth Name (A King Of Thebes) | Male | Greek |
| Peredurus | Name Of A King | Male | Arthurian |
| Peredwus | Name Of A King | Male | Arthurian |
| Persius | Myth Name (Son Of Danae) | Male | Greek |
| Petrus | One Of Joseph's Disciples | Male | Arthurian |
| Phaethusa | Myth Name | Female | Greek |
| Phemius | Myth Name (A Bard) | Male | Greek |
| Pheobus | Shining | Male | Greek |
| Philoetius | Myth Name (A Cowherd) | Male | Greek |
| Phrixus | Myth Name (Son Of Nephele) | Male | Greek |
| Pirithous | Myth Name (Friend Of Theseus) | Male | Greek |