Otto von Habsburg, also known as Archduke Otto of Austria, should have succeeded his father at the throne, but had to go into exile after the collapse of the Austro-Hungarian Empire in 1919.
He was honorary president of the International Paneuropean Union and a former member of the European Parliament for the Christian Social Union of Bavaria (CSU).
Otto von Habsburg, who lived in Poecking in Lower Bavaria, in the last years, also held Croatian citizenship and was a staunch advocate for Croatia's admission to the European Union.