- Orrego Luco, Augusto, 1848-19331
- Ortega Reyes, Manuel, 1819-1908, author1
- Ortega y Fonseca, Francisco.1
- Ortega y Muñiz, Fernando.1
- Ortega, Fernando, active 18931
- Ortega, José de Jesus.1
- Ortega, Lorenzo M.1
- Ortega, Luis F.1
- Orton, James, 1830-18771
- Orton, John J., author1
- Orvañanos, Domingo, author1
- Orvañanos, Domingo.1
- Osborn, Henry Fairfield, 1857-19351
- Osborn, Henry Fairfield, 1857-1935, author3
- Osborn, T. C. (Thomas Childress), 1818- author1
- Osborne, J. W., author1
- Osborne, Oliver T. (Oliver Thomas), 1862-1940 author2
- Osgood, Charles, 1808-18811
- Osgood, David, -1863, author1
- Osgood, Hamilton, 1839-1