| Oglesby, William B., Jr. [Ed.] |
| Oldfield, Dave |
| Oldfileld, David (Photographer) |
| Olive Wyon |
| Oliver Chase Quick |
| Oliver, Jamie |
| Oliver, W.S. (Bill) |
| Ollard, S.L.; Crosse, Gordon; Bond, Maurice F. (eds) |
| Olsen, John |
| Olson, Claudia |
| Omar Khayyam (Edward Fitzgerald translator) |
| Opitz, Judy |
| Oppenheimer, Melanie |
| Oram, R.N. (compiler) |
| Orledge, Robert |
| Orlove, Ben, Ellen Wiegandt and Brian H. Luckman (eds) |
| Orr, David |
| Ortega y Gasset, José |
| Ortiz, Elisabeth Lambert |
| Ortner, Sherry B. |
| Osborne, Harold (editor) |
| Oscar Cullmann |
| Osmond. Marion W. |
| Ostertag, Fritz-Peter und Robert G Koch |
