Andrew John Biemiller (July 23, 1906 in Sandusky, Ohio - April 3, 1982 in Bethesda, Maryland) was a prominent leader of American liberalism in the 20th century.
After graduating from Cornell University in 1926, Biemiller became active in the Socialist Party of America and was a key leader of its "militant" faction, which favored unity of action with the Communist Party USA. In 1932 he went to Milwaukee to work for the Socialist mayor of that city, Daniel Hoan. In 1936 he was elected to the Wisconsin State Assembly as a Socialist, caucusing with the majority Progressive Party who elected him speaker, making him the only minor party speaker of a state legislature in the 20th century.
Biemiller resigned from the Socialist Party when they supported the efforts of Philip La Follette to form a new national party, whom he regarded as a fascist, thus still at that late a date acting in concert with the Communist Party line. He was then elected as a Democrat to congress in 1944, defeated for re-election in 1946 but re-elected again in 1948. During this period Biemiller joined most of the other former Socialist "militants" in helping to found Americans for Democratic Action. He cooperated with Hubert Humphrey in successfully calling for a strong civil rights plank at the 1948 Democratic National Convention.
After serving in Congress, Biemiller served until his death as the chief lobbyist for the AFL-CIO.