男女士名:
| Name | Meaning | Origin | Gender |
| OAKES | Beside the Oak Trees | English | E |
| OAKLEY | Field of Oak Trees | English | E |
| OBEDIENCE | To Obey | American | E |
| OBERON | Bear Heart | German | E |
| OBERT | Wealthy | German | E |
| ODELL | Otter | English | E |
| ODIN | Supreme God | Scandinavian | E |
| OISTIN | Venerable | Latin | E |
| OKAL | To Cross | African | E |
| OKAPI | Animal with Long Neck | African | E |
| OKE | Form of OSCAR | Hawaiian | E |
| OKOTH | Born when it was Raining | African | E |
| OLIN | Of the Ancestors | Scandinavian | E |
| OMEGA | Last | Greek | E |
| ORAN | Green | Celtic/Gaelic | E |
| ORANE | Rising | Greek | E |
| ORDE | Beginning | Latin | E |
| ORDELL | Beginning | Latin | E |
| ORIEL | Gold | French | E |
| ORIEN | The Orient, East | Latin | E |
| ORIOLE | Golden; a gold flecked bird | Latin | E |
| ORION | A Hunter in Greek Mythology | Greek | E |
| ORLEANS | Golden | French | E |
| ORLY | Light | Hebrew | E |
| OVERTON | The Upper Town | English | E |
| OZ | Strength | Hebrew | E |