Daftar cognomina Romawi

Oceanus,
Octavian,
Octavianus,
Octobrianus,
Olennius,
Olympicus,
Opilio,
Opimius,
Opis,
Optatus,
Ordius,
Orientalis,
Orientius,
Orissus,
Orosius,
Osterianus,
Otho,
Ovidus