| Name | # Entries |
|---|---|
| Oswald | 40 |
| Oasis | 40 |
| Overend | 39 |
| Olive | 38 |
| O'toole | 36 |
| Overmeyer | 36 |
| Otaki | 36 |
| O'dwyer | 35 |
| Ogilvy | 34 |
| Ormandy | 34 |
| O'driscoll | 33 |
| Overland | 33 |
| On | 33 |
| Orsmond | 32 |
| Olifant | 30 |
| Okkers | 29 |
| O'gorman | 28 |
| Olwage | 28 |
| Old | 28 |
| Ochse | 27 |
| Ockhuis | 27 |
| Oakes | 26 |
| Obrien | 26 |
| Oneill | 26 |
| Odayar | 26 |
| Ogier | 25 |
| Ogilvie | 25 |
| O'byrne | 25 |
| Orbell | 25 |
| Openshaw | 24 |
| Otara | 24 |
| Orchard | 23 |
| Oconnor | 23 |
| Oldfield | 23 |
| Out | 22 |
| Osler | 22 |
| O'neale | 22 |
| Owers | 21 |
| Otway | 21 |
| O'dowd | 21 |
| Osmond | 21 |
| Over | 20 |
| O'hanlon | 20 |
| Obermeyer | 20 |
| Olympic | 19 |
| Ou | 19 |
| Oelofsen | 19 |
| Odendal | 19 |
| Oxnam | 18 |
| Onekawa | 17 |
| O'kennedy | 17 |
| Orbit | 16 |
| Otten | 16 |
| Oughton | 16 |
| Oppelt | 16 |
| Oak | 16 |
| Orewa | 16 |
| Owies | 16 |
| Organic | 16 |
| Orsborn | 16 |
| Outram | 16 |
| Ott | 15 |
| Ottley | 15 |
| Otene | 15 |
| Oamaru | 15 |
| Ottaway | 15 |
| Ollewagen | 15 |
| Oke | 15 |
| O'riley | 15 |
| Ovens | 15 |
| Orion | 14 |
| Odayan | 14 |
| Oppel | 14 |
| Onehunga | 14 |
| Ollerenshaw | 13 |