Chancellor, President of the National Council, Federal President, founder of two republics: Karl Renner (1870 to 1950) was a social democratic politician of the century who represented the fate of Austria, which had diminished after the fall of the Habsburg Empire, like few others. However, it is not only Renner's approval of the annexation to Nazi Germany that has diminished his reputation over the years; rather, his entire legacy has been called into question. Richard Saage examines in his biography what remains of the legacy of this controversial politician. He takes an open perspective from birth and sheds light on many aspects for the first time in this essential contribution to politics and contemporary history.