Heiner Müller (German: [haɪnɐ mʏlɐ]; 9 January 1929 – 30 December 1995) was a German (formerly East German) dramatist, poet, writer, essayist and theatre director. His "enigmatic, fragmentary pieces" are a significant contribution to postmodern drama and postdramatic theatre.

Müller was born in Eppendorf, Saxony. He joined the Social Democratic Party of Germany in 1946 which was in the course of the forced merger of the KPD and SPD subsumed into the Socialist Unity Party of Germany (Sozialistische Einheitspartei Deutschlands, SED). He was soon expelled for lacking enthusiasm and failing to pay dues. In 1954 he became member of the German Writers' Association (Deutscher Schriftstellerverband). Müller became one of the most important dramatists of the German Democratic Republic and won the Heinrich Mann Prize in 1959 and the Kleist Prize in 1990.

His relationship with the East German state began to deteriorate, however, with his drama Die Umsiedlerin [de] (The Resettler Woman) which was censored in 1961 after only one performance. Müller was expelled from the Writers' Association in the same year. The East German government remained wary of Müller in subsequent years, preventing the premiere of Der Bau (Construction Site) in 1965 and censoring his Mauser [de] in the early 1970s. Yet despite these hardships, Müller's work began to gain popularity both in West Germany and internationally at this time. Many of his best-known plays from this period were premiered in the West: this includes Germania Death in Berlin, which was first performed in 1978 at the Munich Kammerspiele. Heiner Müller himself directed a production of The Mission (Der Auftrag) in Bochum in 1982. In Paris, Jean Jourdheuil [fr] directed the world premiere of Die Hamletmaschine (The Hamletmachine) in 1979. English translations, first by Helen Fehervary and Marc Silberman, then by Carl Weber, introduced Müller to the English speaking world in the mid- and late 1970s; Müller's controversial play Mauser was first performed in 1975 in Austin, Texas.

On 17 November 1976, Müller signed together with eleven other writers and artists the petition against the expatriation of Wolf Biermann. Like several others of the signatories, Müller withdrew his signature on 25 November, according to Biermann on the condition that the Stasi would keep it secret.

Due to his growing worldwide fame, Müller was able to regain acceptance in East Germany. He was admitted to the DDR Academy of Arts, Berlin in 1984 – only two years before he became a member of parallel West Berlin academy. Despite earlier honors, Müller was not readmitted to the East German Writers' Association until 1988, shortly before the end of the GDR. After the fall of the Wall, Müller became final president of the DDR Academy of the Arts from 1990 until its 1993 merger with the western academy.

In 1993 it was alleged that Müller worked from 1979 to 1990 as unofficial collaborator (an informant) under the code name "Heiner" for the East-German Stasi. Müller, who at the time was not a member of the East German Communist Party or the East German Deutscher Schriftstellerverband, admitted that he had contact with Stasi officials, but never provided any material.

In 1992, he was invited to join the directorate of the Berliner Ensemble, Brecht's former company at the Theater am Schiffbauerdamm, as one of its five members along with Peter Zadek, Peter Palitzsch, Fritz Marquardt [de] and Matthias Langhoff [de]. In 1995, shortly before his death, Müller was appointed as the theatre's sole artistic director.

During the last five years of his life, Müller continued to live in Berlin and work all over Germany and Europe, mostly directing productions of his own works. He wrote few new dramatic texts in this time, though, like Brecht, he did produce much poetry in his final years. In the last half-decade of his life, Müller also worked towards transforming the interview into a literary genre.