Postumus (Marcus Cassianius Latinius Postumus, died 269) was a Roman usurper and founder of the Gallic Empire.
Postumus may also refer to: Agrippa Postumus (12 BC – 14 AD), son of Marcus Vipsanius Agrippa Postumus Junior (died 268), alleged son of the Gallic emperor Poenius Postumus (died 60/61 AD), prefect of II Legion Augusta at the time of Boudica’s revolt Postumus (praenomen), Roman praenomen
See also Posthumous (disambiguation)