Alexander Schwab (5 July 1887 – 12 November 1943) was a German political activist. He withdrew from active participation in politics after resigning from the fractious and short-lived Communist Workers' Party ("Kommunistische Arbeiter-Partei Deutschlands" / KAPD) in 1922, but continued his contribution as an independent left of centre commentator-journalist. During the twelve Nazi years he was arrested at least twice, spending the final years of his life, between 1936 and 1943, in a succession of jails. Sources may also identify him by the pseudonym under which some of his contributions were published, as Albert Sigrist Sachs.

Alexander Schwab was born into a Protestant family in Stuttgart. He grew up in Danzig where his father Karl Julius Schwab, a musician and composer, was in charge of the music ("als Opernkappelmeister") at the city opera house. He attended a Gymnasium (secondary school) in Danzig and then moved on to study Philosophy, Germanistics, Classical languages, Applied Economics ("Nationalökonomie"), Sociology and Civil law at Rostock, Jena, Heidelberg and Freiburg i.B. At university he participated actively in the Freestudenthood, a grouping of students who were expressly not members of the more traditional student fraternities. He was also a member of the politically left-of-centre Wandervogel hiking movement. Alexander Schwab received his doctorate from Heidelberg University in 1913. His doctoral dissertation was entitled "The influence of consumption on the German furniture industry and production" ("Der Einfluß der Konsumtion auf Möbelindustrie und Möbelproduktion in Deutschland"), but when it was published two years later it was under the shorter title "Möbelkonsumtion und Möbelproduktion in Deutschland".

For a year following the award of his doctorate, during 1913/14, Schwab taught at the Wickersdorf Free School Community, a progressive school that had been founded by the controversial education pioneer Gustav Wyneken in the countryside south of Erfurt in 1906. Several historians describe Schwab during this period as one of the leading intellects of the influential Free German Youth movement. In October 1913 he participated in the first ever Free German Youth Day in the Hoher Meißner hills north of Frankfurt. In the months before the war he also involved himself in conceptualising and organising democratically elected "General Student Committees" ("Allgemeiner Studenten-Ausschüsse").

Around this time Schwab and some of his intellectual friends rented a large house in Jena and embarked on what was seen at the time as a remarkable experiment in cohabitation, whereby four unmarried young men and four unmarried young women all lived together in the one house. On 8 May 1914 the unmarried status of two members of the cohabiting community ended when Alexander Schwab married Dr Hildegard Felisch: it was her twenty-fifth birthday.

At the end of July 1914 war broke out. Alexander Schwab lost little time in volunteering for the army. He was very quickly rejected for military service, however, on account of a pulmonary hemorrhage ("Lungen-Blutsturz"). He was instead sent to a desk job in the war supplies department. Later he found himself working in Dresden at the "Jasmatzi" cigarette factory.

Despite having volunteered for military service in 1914, by 1918 Alexander Schwab had joined the anti-war movement. He became friendly with the radical socialist educationalist Otto Rühle (1874–1943) and with the young artist Conrad Felixmüller. In 1917 Schwab joined the Independent Social Democratic Party ("Unabhängige Sozialdemokratische Partei Deutschlands" / USPD) which had broken away from the mainstream Social Democratic Party ("Sozialdemokratische Partei Deutschlands" / SPD) following an intensification of internal party ructions over funding for the war. The next year he joined the Spartacus League: he was numbered among the close friends of the movement's best-known founders, Karl Liebknecht and Rosa Luxemburg.

At the end of the year the Communist Party of Germany emerged from the USPD, founded formally at a three-day conference in Berlin between 30 December 1918 and 1 January 1919. Schwab found himself on the left wing of the Communist Party, collaborating closely with Karl Schröder (1884–1950). Beyond the world of party politics, directly following the revolutions of 1918/19, he teamed up with the teacher Frieda Winckelmann (1873–1943) and others to set up a "Free academy community for proletarians" ("Freie Hochschulgemeinde für Proletarier") from which emerged, in the first part of 1919, the "Soviet school of the Greater Berlin labour movement" ("Räteschule der Groß-Berliner Arbeiterschaft"). Barely two years later the institution became insolvent and was taken over by the trades unions.

The parties of the left were prone to fragment during this period, and in 1920 Alexander Schwab and his friend Karl Schröder were founder members of the Communist Workers' Party ("Kommunistische Arbeiter-Partei Deutschlands" / KAPD), becoming a leading ideological strategist of its Berlin group. In June/July 1921 he led the KAPD delegation to the third world congress of the Communist International (Comintern), held in Moscow. He was sharply critical of Comrade Lenin's political tactics in respect of western Europe: the speeches he contributed were published in the congress minutes, using the cover name "Sachs" to identify him.