Fritz Tarnow (April 13, 1880 in Bad Oeynhausen, Province of Westphalia – October 23, 1951) was a Social Democrat trade unionist and Reichstag deputy during the Weimar Republic.
He was one of the leading figures in the national executive of the Allgemeiner Deutscher Gewerkschaftsbund, a German trade union confederation.
During the Great Depression he advocated, alongside Vladimir S. Voitinsky, a proto-Keynesian public works program dubbed the WTB plan.
After Adolf Hitler's rise to power in early 1933 and the dismantling of the trade unions, Tarnow was arrested on 2 May.
Hans Staudinger, who had been a State Secretary in the Prussian Ministry of Trade until the Preußenschlag, succeeded in obtaining Tarnow's release from Gestapo custody.