| Oswald | Man | English Names |
| Oswine | Man | English Names |
| Oswulf | Man | English Names |
| Otis | Man | English Names |
| Overton | Unisex | English Names |
| Owl | Unisex | English Names |
| Oxford | Man | English Names |
| Ozzie | Man | English Names |
| Ozzy | Man | English Names |
| Pace | Unisex | English Names |
| Pacey | Man | English Names |
| Paddington | Unisex | English Names |
| Pagan | Unisex | English Names |
| Page | Unisex | English Names |
| Paget | Unisex | English Names |
| Paige | Woman | English Names |
| Painter | Unisex | English Names |
| Paley | Unisex | English Names |
| Palmer | Man | English Names |
| Pam | Woman | English Names |