Karl Schröder (November 13, 1884 in Polzin – April 6, 1950 in Berlin) was a communist politician and writer.
Schröder was the son of a teacher. He went to Berlin where he studied philosophy, literature, history and art history. He gained his doctorate with a dissertation on art history. He then worked as a private tutor. By 1913 he was a member of the Social Democratic Party of Germany (SPD) and in 1914 became a research assistant at the SPD Zentralbildungsausschuss for workers' education. During this period, he became friends with Franz Mehring and developed his connection to the labor movement.
After participating in the First World War, Karl Schroeder joined the Spartacus League in 1918, and shortly afterwards was appointed editor of Rote Fahn (Red Flag), the central organ of the Communist Party (KPD). In 1919 he was expelled from the KPD along with the majority of the party who went on to form the Communist Workers Party of Germany (KAPD). Alongside Alexander Schwab, he rose to become a leading member of the KAPD and the editor of the Arbeiter-Zeitung (Workers newspaper). He travelled to Moscow where he met Lenin, Trotsky and Bukharin. After the Third Congress of the Comintern (June 22-July 12, 1921), he distanced himself from the Comintern and was expelled from the KAPD in 1922 as leader of the Essen Tendency.
After the attempt to develop the KAPD in Essen failed, Schröder returned to the SPD at the instigation of Paul Levi. In subsequent years, he became a novelist, editor and publisher active in the social democratic workers' education service. He was also active in the Sozialistische Arbeiter-Jugend (SAJ). As Schröder retained his Councilist approach, and sought to gain support for these views in the SAJ and SPD, this could be regarded as entryism.