The emperor of Austria was the ruler of the Austrian Empire and later the Austro-Hungarian Empire. The hereditary imperial title and office was proclaimed in 1804 by Francis II, Holy Roman Emperor, a member of the House of Habsburg-Lorraine, and continually held by him and his heirs until Charles I relinquished power in 1918.

The Kingdom of Hungary between 1526 and 1867 existed as a state outside the Holy Roman Empire, but part of the lands of the Habsburg monarchy that became the Austrian Empire in 1804. After the Battle of Mohács in 1526, the country was ruled by two crowned kings. Initially, the exact territory under Habsburg rule was disputed because both rulers claimed the whole kingdom. This unsettled period lasted until 1570 when John Sigismund Zápolya abdicated as King of Hungary in Emperor Maximilian II's favor.