Gustaf Allan Pettersson (19 September 1911 – 20 June 1980) was a Swedish composer. Today he is considered one of the most important Swedish composers of the 20th century. His symphonies developed a devoted international following, starting in the final decade of his life.
Pettersson, the youngest of four children of a violent, alcoholic blacksmith, was born at the manor of Granhammar in Västra Ryd parish in the province of Uppland, but grew up in poor circumstances in the Södermalm district of , where he resided during his whole life. He once said of himself: "I wasn't born under a piano, I didn't spend my childhood with my father, the composer... no, I learnt how to work white-hot iron with the smith's hammer. My father was a smith who may have said no to God, but not to alcohol. My mother was a pious woman who sang and played with her four children."
In 1930, he began study of violin and viola, as well as counterpoint and harmony, at the conservatory of the Royal Swedish Academy of Music (). He became a distinguished viola player, but also started composing songs and smaller chamber works in the 1930s. At the beginning of World War II he was studying the viola with Maurice Vieux in Paris. During the 1940s he worked as a violist in the Stockholm Concert Society (later the ), but also studied composition privately with Karl-Birger Blomdahl, Tor Mann, and Otto Olsson. His production from this decade include the song cycle twenty-four Barefoot Songs (1943–45) based on own poems and a dissonant concerto for violin and string quartet (1949). Latter work is influenced by Béla Bartók and Paul Hindemith.
In 1951, Pettersson created the experimental Seven Sonatas for two Violins. At the same time he also composed the first of his seventeen symphonies, which he left unfinished. This work has recently been recorded in a performing version prepared by trombonist and conductor Christian Lindberg. In September 1951, he went to Paris to study composition, having been a student of René Leibowitz, Arthur Honegger, Olivier Messiaen, and Darius Milhaud. Pettersson returned to Sweden at the end of 1952. The next year 1953 he was given the diagnosis rheumatoid arthritis. Pettersson about the symphonic output of this decade: "No one in the 1950s noticed, that I am always breaking up the structures, that I was creating a whole new symphonic form."