Flavius Dalmatius (died June 337),[1] often spelled Delmatius on contemporary coins, was a Caesar of the Roman Empire from 335 to 337, and member of the Constantinian dynasty.

His father, also named Flavius Dalmatius, was the half-brother of Constantine and served as censor.

Dalmatius and his brother Hannibalianus were educated at Tolosa (Toulouse) by rhetor Exuperius.

On 18 September 335, he was raised to the rank of Caesar by his uncle, with the control of Thracia, Achaea and Macedonia.

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 imperial power other than the sons of the late emperor.