| Next | Last |
| NAME | MEANING | GENDER | ORIGIN |
| OAKES | Beside the Oak Trees | E | English |
| OAKLEY | Field of Oak Trees | E | English |
| OBEDIENCE | To Obey | E | American |
| OBELIA | Needle | F | Greek |
| OBERON | Bear Heart | E | German |
| OBERT | Wealthy | E | German |
| OCEAN | Sea | F | Greek |
| OCEANA | From the Sea | F | Greek |
| OCTAVIA | The Eighth | F | Latin |
| OCTAVIO | The Eighth | M | Latin |
| OCTAVIOUS | Eighth | M | Latin |
| OCTAVIUS | The Eighth | M | Greek |
| OCTOBER | Born in October | E | American |
| ODAKOTA | Friend | M | Native American |
| ODED | Strong | M | Hebrew |
| ODEDA | Strong | F | Hebrew |
| ODELE | Wealthy, Melody | F | Greek |
| ODELIA | I will praise God | F | Greek |
| ODELL | Otter | E | English |
| ODESSA | The Odyssey | F | Latin |
| ODETTA | Ode | F | French |
| ODETTE | Ode, Melodic | F | French |
| ODIN | Supreme God | E | Scandinavian |
| ODINA | Mountain | F | Latin |
| ODYSSEUS | Full of Wrath | M | Greek |
| OFIRA | Gold | F | Hebrew |
| OGDEN | From the Valley of Oaks | M | English |
| OHANZEE | Shadow | M | Native American |
| OHIO | Large River | E | Native American |
| OIHANE | From the Forest | F | Spanish |
| OISTIN | Venerable | E | Latin |
| OJAL | Vision | F | Sanskrit (India) |
| OJAS | Strong One | M | Sanskrit (India) |
| OKAL | To Cross | E | African |
| OKALANI | Heaven | F | Hawaiian |
| OKAPI | Animal with Long Neck | E | African |
| OKE | Form of OSCAR | E | Hawaiian |
| OKI | Ocean Centered | F | Japanese |
| OKLAHOMA | Red People | E | Native American |
| OKOTH | Born when it was Raining | E | African |
| OKSANA | God is With Us | F | Slavic |
| OLAF | Ancestor | M | Scandinavian |
| OLATHE | Lovely, Beautiful | F | Native American |
| OLE | Ancestor | M | Scandinavian |
| OLEG | Sacred | M | Slavic |
| Next | Last |