Otto Muehl (16 June 1925 – 26 May 2013) was an Austrian artist, who was known as one of the co-founders as well as a main participant of Viennese Actionism and for founding the Friedrichshof Commune.

In 1943, Muehl had to serve in the German Wehrmacht. There he registered for officer training. He was promoted to lieutenant, and in 1944 he took part on infantry battles in the course of the Ardennes Offensive.

After the war, he studied teaching German and History, and Pedagogy of Art at the Wiener Akademie der bildenden Künste.

In 1972 he founded the Friedrichshof Commune, which has been viewed by some as an authoritarian sect, and that existed for several years before falling apart in the 1990s. In 1991, Muehl was convicted of sexual offences with minors and drugs offences and sentenced to 7 years imprisonment. He was released in 1997, after serving six and a half years, and set up a smaller commune in Portugal. After his release, he also published his memoirs from the prison (Aus dem Gefängnis).