 | Oak, J. Quercus (Fictitious character) (1) |
| | O'Brien, John A. (John Anthony), 1893-1980 (1) |
| | O'Bryon, Father (Fictitious character) (3) |
| | O'Connell, Daniel, 1775-1847 (1) |
| | Oddud (Fictitious character) (4) |
| | Old Axel (Fictitious character) (1) |
| | Oldham, Wally (Fictitious character) (1) |
| | Old Jasper (Fictitious character) (1) |
| | Old Stormalong (Fictitious character) (1) |
| | Old Traveler (Fictitious character) (2) |
| | Olson, Mr. (Fictitious character) (1) |
| | Oolik (Fictitious character) (1) |
| | Osceola, Jim (Fictitious character) (1) |
| | Otto (Fictitious character) (49) |
| | Owens, Jesse, 1913- (1) |
