After 1949, many former Austrian National Socialists reorganized in the Federation of Independents (VdU, Verband der Unabhängigen) and its successor party, the Austrian Freedom Party (FPÖ, Freiheitliche Partei Österreichs). As the first party leader of the FPÖ beginning in 1955/56, Anton Reinthaller (1895–1958) played a central role in the postwar political mobilization of former National Socialists, known in Austria as the Ehemaligen (formers). On the basis of the hitherto unused personal papers of Anton Reinthaller, Margit Reiter's contribution sketches the political career of the founder of the FPÖ from his time as a member of the illegal National Socialist Party during the era of Austrofascism, through his appointment as a Nazi minister in 1938 and to various other positions during the Nazi period, to his postwar denazification and reentry into politics. The correspondence, personal notes, and court documents contained in his papers not only provide a good overview of the networks and the discourse among former Nazis after 1945, but also allow for an investigation into Reinthaller's attitude towards National Socialism and his retrospective self-presentation in front of the denazification court. The early history of the FPÖ is analyzed by interweaving party history with a biographical approach. In its tension between biographical and ideological continuities, on the one hand, and a willingness and ability to adapt to changed political circumstances, on the other, the example of Anton Reinthaller reveals a typical "Austrian" perpetrator biography of a sort that has been neglected in historical research.