Antun Mavrak (1899-1938) was a Croatian revolutionary and top functionary of the Communist Party of Yugoslavia (KPJ). Mavrak was named as organizational secretary of the underground KPJ in August 1930 and remained in that leading post until his removal in December 1931. Although expelled from the Communist Party, Mavrak continued to live in the Soviet Union under the name Karl Yakovlevich, working as a laborer. Mavrak was arrested during the Terror of 1937-38 and was executed as an alleged spy in 1938. Mavrak was posthumously rehabilitated by the Soviet government in 1963.