Karl Freiherr von Fischer-Treuenfeld (31 March 1885 – 7 June 1946) was a German Waffen-SS commander. A brigade commander during the Nazi era, during the invasion of the Soviet Union, he commanded the 2 SS Infantry Brigade and the 1 SS Infantry Brigade, which engaged in the murder of Jews, communists and partisans (bandits). Treuenfeld later commanded the SS Division Frundsberg. He committed suicide in 1946 whilst in American custody.