They first appear in history during the late Republic, remaining on the periphery of the Roman aristocracy until the time of Nero.
Roman empress Milonia Caesonia, the last wife of the emperor Caligula was presumably descended from the Caesonii, as she bore their nomen.
[5] The Caesonii of the second and third centuries appear to have been an unremarkable family, of senatorial or equestrian rank, which eventually was elevated to the patriciate, holding many of the most important offices in the Roman state.
This branch of the family may have originated in Latium or the surrounding region, perhaps the town of Antium.
[6] The name may derive from the root caesius, meaning "blue-grey," a word frequently used to describe the color of the eyes.