Flavius Dalmatius (died 337), also known as Dalmatius Caesar, was a Caesar (335–337) of the Roman Empire, and member of the Constantinian dynasty.
Dalmatius was son of another Flavius Dalmatius, censor, and nephew of Constantine I. Dalmatius and his brother Hannibalianus were educated at Tolosa (Toulouse) by rhetor Exuperius.
Division of the Roman Empire among the Caesars appointed by Constantine I: from left to right, the territories of Constantine II, Constans I, Dalmatius and Constantius II. After the death of Constantine I (May 337), this was the formal division of the Empire, until Dalmatius was killed and his territory divided between Constans and Constantius.
On 19 September 335, he was raised to the rank of Caesar, with the control of Thracia, Achaea and Macedonia. Dalmatius died in late summer 337, killed by his own soldiers. It is possible that his death was related to the purge that hit the imperial family at the death of Constantine, and organized by Constantius II with the aim of removing any possible claimant to the throne.
