Author
- Obsequens, Julius 1
- Octavianus early 6th cent. 1
- Odo Saint, Abbot of Cluny ca. 879-942 1
- Odo, of Cheriton, d. 1247 1
- Opilius, Aurelius, 1st cent. B.C. 1
- Oppius, C. 1st cent. B.C. 1
- Optatus, Saint, Bishop of Mileve active 4th century 2
- Orbilius Pupillus, L. (Lucius), ca. 114-ca. 14 B.C 1
- Orientius, Saint, active 430-440 3
- Orosius, Paulus 3
- Ovid 43 B.C.-17 or 18 A.D 20
