Occam, Guillelmus de/Ockham, William of (ca. 1285-ca. 1349)

Ollé-Laprune, Léon (1839-1898)

Origenes Adamantius (ca. 185-253/4)

Ortega y Gasset, José (1883-1955)

Ovidius Naso, Publius (43 B.C.-17/18)

Owen, Robert (1771-1858)