Otto I (Francis Joseph Otto Robert Mary Anthony Charles Max Henry Sixtus Xavier Felix Renatus Louis Gaetan Pius Ignatius, German: Franz Joseph Otto Robert Maria Anton Karl Max Heinrich Sixtus Heinrich Sixtus Xavier Felix Renatus Ludwig Gaetan Pius Ignatius) was Emperor of Austria, King of Hungary etc, and thus the ruler of the Austrian-Hungarian Empire.
He was born on 20 November 1912 in Reichenau an der Rax, Lower Austria, and died 4 July 2011 in Vienna. He was the oldest son of Emperor Charles I and his wife Zita, née Princess of Bourbon-Parma.
He became ruler of the Austrian-Hungarian Empire upon the death of his father on 1 April 1922. Otto I's empire participated in the third German-French war, on the German Empire's side, 1939-1945.
He married on 10 May 1951 to Princess Regina of Saxe-Meiningen (1925-2010), a daughter of Duke George of Saxe-Meiningen and his wife Countess Klara Maria von Korff genannt Schmissing-Kerssenbrock, having the following the issue:
Andrea (born 1953)
Monica (born 1954)
Michaela (born 1954)
Gabriela (born 1956)
Walburga (born 1958), married to the Swedish Count Archibald Douglas
Charles (born 1961), who succeeded his father as Charles II
George (born 1964)