| O'Brien | 50 |
| O'Connor | 63 |
| O'Donahue | 254 276 |
| O'Hara | 291 293 380 |
| O'Neal | 183 |
| O'Reilly | 22 23 87 181 259 351 352 382 466 513 |
| O'Toole | 151 352 381 384 |
| Oakes | 225 |
| Olden | 59 |
| Oldham | 495 |
| Olean | 176 |
| Oliphant | 293 |
| Olness | 321 |
| Olsen | 78 79 110 177 293 306 322 349 350 442 477 478 484 |
| Olson | 114 136 141 180 194 506 513 |
| Opheim | 292 293 |
| Opitz | 388 389 |
| Opsahl | 276 |
| Oquist | 69 77 173 175 187 216 225 232 248 287 289 292 350 351 382 386 437 442 498 |
| Orr | 114 446 451 |
| Ortell | 499 |
| Osgood | 303 |
| Osse | 355 |
| Oster | 289 |
| Osterman | 276 |
| Otto | 245 |
| Overby | 293 |
| Overgard | 452 469 470 |
| Owens | 279 |
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