Octavius Augustus, [23]

Olivier, [70]

Omeyads, [66], [67], [72], [74]

Opus Majus, [87]

Ordoño I, [79]

Osca, [25]

Ostrogoths, [36]

Paladins, [70]

Pedro, [83], [95]

Pelagius, [64]