Count Theodosius, also known as Flavius Theodosius, a senior military officer serving in the western part of the Roman Empire. He is credited with being the founding member of the House of Theodosius.
He was sent to Britain in 368 to deal with a barbarian invasion of the Roman provinces in that island, which he dealt with successfully. On his return, he succeeded Jovinus as the magister equitum praesentalis at the court of the emperor Valentinian I. In 373 he was made commander of the expedition to suppress the rebellion of Firmus in Mauretania, but following his victory over Firmus, Theodosius was arrested, taken to Carthage, and executed in early 375. The reasons for his execution are not clear.