The Austrian Empire (Austrian German: Kaiserthum Oesterreich, modern spelling Kaisertum Österreich) was a Central European multinational great power from 1804 to 1867 created by proclamation out of the realms of the Habsburgs. It was the third most populous empire after Russia and France. Along with Prussia, it was one of the two major powers of the German Confederation. Geographically, it was the second largest empire in Europe after the Russian Empire (621,538 square kilometres). Proclaimed in response to the First French Empire, it overlapped with the Holy Roman Empire until the latter's dissolution in 1806. The Ausgleich of 1867 elevated Hungary's status. It became a separate entity from the Empire entirely, joining with it in the dual monarchy of Austria-Hungary.
The Austrian Empire was also a constituent part of Austria-Hungary, the Emperor being Emperor of Austria and King of Hungary separately, and not Emperor of Austria-Hungary.