| Name | # Entries |
|---|---|
| Omanu | 9 |
| Ordish | 8 |
| Organ | 8 |
| Orica | 8 |
| Orient | 8 |
| Osbourne | 8 |
| Overington | 8 |
| Oceanic | 8 |
| O'conner | 8 |
| O Donnell | 8 |
| O'hare | 8 |
| O'hearn | 8 |
| Ollington | 8 |
| Opal | 8 |
| Odell | 8 |
| Oktober | 8 |
| Ortmann | 8 |
| Opsm | 7 |
| Origin | 7 |
| Orpwood | 7 |
| Orrell | 7 |
| Ortega | 7 |
| Orthodontists | 7 |
| Oscar | 7 |
| Osgood | 7 |
| Otimi | 7 |
| Otter | 7 |
| Otton | 7 |
| Outback | 7 |
| Outline | 7 |
| Overall | 7 |
| Oyster | 7 |
| Oats | 7 |
| O'flynn | 7 |
| Open | 7 |
| Oliviera | 7 |
| Oncker | 7 |
| Orrie | 7 |
| Orams | 6 |
| Oranga | 6 |
| Oregon | 6 |
| Ormerod | 6 |
| Osbaldiston | 6 |
| Oskam | 6 |
| Otane | 6 |
| Owaka | 6 |
| Oliver's | 6 |
| Olphert | 6 |
| Om | 6 |
| Omahu | 6 |
| Omalley | 6 |
| Omokoroa | 6 |
| Ongley | 6 |
| Onsite | 6 |
| Orffer | 6 |
| O'ehley | 6 |
| Osner | 6 |
| Okeke | 6 |
| Olden | 6 |
| Olinsky | 6 |
| Okoro | 6 |
| Offerman | 6 |
| Omer | 6 |
| Orca | 5 |
| Oriental | 5 |
| O'rorke | 5 |
| O'rourke | 5 |
| Orpin | 5 |
| Orringe | 5 |
| Osment | 5 |
| Ostend | 5 |
| Oswin | 5 |
| Ota | 5 |
| Otorohanga | 5 |
| Oud | 5 |