Flavius Theodosius or Theodosius the Elder is a senior military officer serving in the Western Roman Empire and the father of the Roman emperor Theodosius I. Flavius Theodosius attains the rank of Comes Britanniarum (Count of the province of Britannia) and as such, he is usually referred to as Comes (Count) Theodosius.

He afterwards fights against the Alemanni and in Mauretania.