Boys names beginning with O (1/12):
| O' | O'brian | O'brien | O'keefe |
| O'shay | O'shea | Oakden | Oakes |
| Oakley | Obadiah | Obediah | Ocelfa |
| Ociel | Octave | Octe | Octha |
| Octha | Ocumwhowurst | Ocunnowhurst | Ocvran |
| O' | O'brian | O'brien | O'keefe |
| O'shay | O'shea | Oakden | Oakes |
| Oakley | Obadiah | Obediah | Ocelfa |
| Ociel | Octave | Octe | Octha |
| Octha | Ocumwhowurst | Ocunnowhurst | Ocvran |