| Name | # Entries |
|---|---|
| Oosthuizen | 1299 |
| Olivier | 1186 |
| Oliver | 921 |
| O'connor | 910 |
| O'brien | 889 |
| O'neill | 648 |
| Osborne | 644 |
| Olsen | 543 |
| Owen | 533 |
| O'sullivan | 427 |
| Odendaal | 415 |
| O'connell | 414 |
| O'donnell | 385 |
| Otto | 333 |
| Orr | 317 |
| Opperman | 306 |
| Omar | 289 |
| Oberholzer | 278 |
| O'leary | 256 |
| O'reilly | 202 |
| Owens | 182 |
| Oliphant | 178 |
| October | 174 |
| Ogle | 173 |
| Osman | 170 |
| Ormsby | 161 |
| O'malley | 147 |
| O'callaghan | 136 |
| Oakley | 125 |
| O'hara | 107 |
| Oldham | 105 |
| Osborn | 96 |
| Olliver | 94 |
| Oliveira | 93 |
| O'neil | 92 |
| Oates | 91 |
| O'donoghue | 90 |
| O'shea | 88 |
| Otago | 81 |
| O'loughlin | 79 |
| Olson | 77 |
| Ormond | 76 |
| O'dea | 74 |
| O'keeffe | 74 |
| O'halloran | 72 |
| O'hagan | 70 |
| O'grady | 70 |
| Overton | 69 |
| O'kane | 69 |
| Orange | 69 |
| O'regan | 69 |
| Ocean | 68 |
| O'keefe | 68 |
| Ogden | 64 |
| Oelofse | 63 |
| Oosthuysen | 62 |
| Oudtshoorn | 59 |
| Office | 59 |
| Oberholster | 58 |
| Ontong | 56 |
| Ong | 56 |
| Oram | 54 |
| Omarjee | 54 |
| Orton | 52 |
| O'carroll | 51 |
| Ohlson | 49 |
| Oxley | 49 |
| Opus | 47 |
| Oxford | 47 |
| Oxenham | 46 |
| Onselen | 43 |
| One | 43 |
| O'flaherty | 41 |
| O'shaughnessy | 41 |
| Olckers | 40 |