The Military Frontier was a province straddling the southern borderland of the Habsburg Monarchy and later the Austrian and Austro-Hungarian Empire. It acted as the cordon sanitaire against incursions from the Ottoman Empire.

When created in the 16th century by Ferdinand I, the region was divided into two districts under special military administration: the Croatian Military Frontier and the Slavonian Military Frontier. Initially, the Military Frontier came under the jurisdiction of the Croatian Sabor and ban but, in 1627, it was placed under the direct control of the Habsburg military. For more than two centuries, they would retain complete civilian and military authority over the area, up to the abolition of the Military Frontier in 1881.