Siegfried Aufhäuser (1 May 1884 – 6 December 1969) was a German politician and union leader who was chairman of the white-collar General Federation of Free Employees (AfA-Bund) from 1921 until 1933. Aufhäuser joined the Independent Social Democratic Party of Germany (USPD) in 1918 before becoming a member of the Social Democratic Party of Germany (SPD) after the USPD's dissolution in 1922. He was a member of the Reichstag from 1921 to 1933. A prominent member of the party's left-wing, he viewed the political reality of the Weimar Republic from the perspective of class struggle, emphasising the role of trade unions in politics. After the Nazi rise to power, Aufhäuser was arrested several times in 1933 and fled into exile in May. He was expelled from the SPD in 1935 for advocating an allianc