| Oaklynn | Woman | American Names |
| October | Unisex | American Names |
| Odonna | Woman | American Names |
| Olencia | Woman | American Names |
| Olenna | Woman | American Names |
| Oleta | Woman | American Names |
| Olicia | Woman | American Names |
| Olinda | Woman | American Names |
| Olisa | Woman | American Names |
| Omarion | Man | American Names |
| Ondre | Man | American Names |
| Oralee | Woman | American Names |
| Oralia | Unisex | American Names |
| Orenthal | Man | American Names |
| Orlena | Woman | American Names |
| Ornice | Woman | American Names |
| Orrtha | Woman | American Names |
| Oshae | Unisex | American Names |
| Osma | Woman | American Names |
| Oxide | Unisex | American Names |