| Name | # Entries |
|---|---|
| Oneill | 24 |
| Office | 23 |
| Out | 22 |
| Orbell | 22 |
| Oconnor | 21 |
| Owers | 20 |
| Otway | 20 |
| Obermeyer | 20 |
| Olympic | 19 |
| Oliphant | 19 |
| Ou | 18 |
| Oxnam | 18 |
| O'neale | 18 |
| Onekawa | 17 |
| Over | 17 |
| O'dowd | 17 |
| Oppelt | 16 |
| Orbit | 16 |
| Oak | 16 |
| Orewa | 16 |
| Osmond | 16 |
| O'hanlon | 16 |
| Organic | 16 |
| Otene | 15 |
| Oughton | 15 |
| Ollewagen | 15 |
| Oamaru | 15 |
| Olivier | 15 |
| Ottaway | 15 |
| Outram | 15 |
| Odayan | 14 |
| Orion | 14 |
| Ottley | 14 |
| O'riley | 14 |
| Onehunga | 14 |
| Orsborn | 14 |
| Ortell | 13 |
| Ollerenshaw | 13 |
| Osrin | 13 |
| Oakden | 13 |
| Oke | 13 |
| Ormrod | 13 |
| Orchard | 12 |
| Olwagen | 12 |
| Oberem | 12 |
| Oleary | 12 |
| Ormiston | 12 |
| O'boyle | 11 |
| Odlum | 11 |
| Ott | 11 |
| Ovenden | 11 |
| Oborn | 11 |
| O'donovan | 11 |
| Olliff | 11 |
| Oosthuizen | 11 |
| Openshaw | 11 |
| O'shannessey | 11 |
| Oconnell | 11 |
| Ovens | 11 |
| Oosthuisen | 10 |
| Off | 10 |
| Oil | 10 |
| Olney | 10 |
| Opotiki | 10 |
| Ooka | 10 |
| Omar | 10 |
| Orren | 10 |
| Ora | 9 |
| Otahuhu | 9 |
| Oceans | 9 |
| Otis | 9 |
| Ockwell | 9 |
| Odlin | 9 |
| Omanu | 9 |
| Osten | 9 |