| Name | # Entries |
|---|---|
| Otte | 13 |
| Ortell | 13 |
| Oakden | 13 |
| O'donovan | 13 |
| Orpen | 13 |
| Osrin | 13 |
| O'kelly | 13 |
| Opie | 13 |
| Ormrod | 13 |
| Osmany | 12 |
| Olwagen | 12 |
| Oleary | 12 |
| Ormiston | 12 |
| Orrell | 12 |
| Oellermann | 12 |
| Oberem | 12 |
| Oconnell | 12 |
| Oostendorp | 12 |
| Olver | 12 |
| O'boyle | 11 |
| Odlum | 11 |
| Olney | 11 |
| Organ | 11 |
| Oscroft | 11 |
| Ovenden | 11 |
| Oborn | 11 |
| O'farrell | 11 |
| Olliff | 11 |
| O'shannessey | 11 |
| O'hare | 11 |
| Orpwood | 11 |
| Off | 10 |
| Oil | 10 |
| Opotiki | 10 |
| Oosthuisen | 10 |
| Ooka | 10 |
| Overall | 10 |
| Oosthuyzen | 10 |
| Orren | 10 |
| Oppenheimer | 10 |
| Otter | 10 |
| Ora | 9 |
| Orford | 9 |
| Oerson | 9 |
| Otahuhu | 9 |
| Oudshoorn | 9 |
| Oats | 9 |
| Oceans | 9 |
| O'conner | 9 |
| Osbourne | 9 |
| Osterloh | 9 |
| Otis | 9 |
| Overington | 9 |
| Olds | 9 |
| Ockwell | 9 |
| Odlin | 9 |
| Oertel | 9 |
| Omanu | 9 |
| Ormerod | 9 |
| Osten | 9 |
| Otaika | 9 |
| Orgill | 9 |
| Ovenstone | 9 |
| Os | 9 |
| Odgers | 8 |
| O'hearn | 8 |
| O'meara | 8 |
| Opal | 8 |
| Oppenheim | 8 |
| Ortega | 8 |
| Ordish | 8 |
| Odell | 8 |
| Ornelas | 8 |
| Oldewage | 8 |
| Oever | 8 |