Karl of Austria (also known in English as Charles) Karl Franz Josef Ludwig Hubert Georg Maria von Habsburg (August 17, 1887 - April 1, 1922) was the last Emperor of Austria and the last King of Hungary (as Charles IV of Hungary) and of the Habsburg Dynasty. He reigned from 1916 until his abdication on November 11, 1918. He sought to reclaim the throne of Hungary in the early 1920s.

Karl has generally been seen by historians as an honourable figure who tried as emperor-king to halt World War I. On 14 April 2003 the Vatican's Congregation for the Causes of Saints, in the presence of Pope John Paul II, promulgated Karl of Austria's "heroic virtues", a step on the road to sainthood in Roman Catholicism.

Karl was the son of Archduke Otto Franz Joseph, younger brother of the Archduke Franz Ferdinand (whose assassination triggered off World War I), and of Princess Josepha of Saxony. In 1911 he was married to Princess Zita of Bourbon-Parma, a daughter of the exiled Duke of Parma. Their oldest son and current head of the Habsburg family is Otto von Habsburg, who served as a German Member of the European Parliament.

Names in other languages of the Austro-Hungarian Empire: German: Karl I, Czech: Karel I, Slovak: Karol IV, Hungarian: IV Károly

Preceded by:
Franz Josef of Austria
Emperors of Austria Succeeded by:
monarchy and empire abolished and replaced with republics