The Slavonian Military Frontier ( or ) was a district of the Military Frontier, a territory in the Habsburg Monarchy, first during the period of the Austrian Empire and then during the Austro-Hungarian Monarchy. It was formed out of territories the Habsburgs conquered from the Ottoman Empire and included southern parts of Slavonia and Syrmia; today the area it covered is mostly in eastern Croatia, with its easternmost parts in northern Serbia (mostly in Vojvodina region).