Aribert Reimann (born 4 March 1936 in Berlin) is a German opera composer, pianist and accompanist, known especially for his literary operas. His version of King Lear was written at the suggestion of Dietrich Fischer-Dieskau who sang the title role.

After studying composition, counterpoint and piano (under, among others, Boris Blacher) at the Berlin University of the Arts, Reimann took a job as a repetiteur at the Deutsche Oper in Berlin. His first appearances as a pianist and accompanist were towards the end of the 1960s. In the early 1970s, he became a member of the Akademie der Künste in Berlin, and held a professorship in contemporary song at Berlin's Hochschule der Künste from 1983 to 1998.

Reimann's reputation as a composer has increased greatly with several great literary operas, including Lear and Das Schloss (The Castle). Besides these, he has written chamber music, orchestral works and songs. He has been honoured repeatedly, including the Großen Verdienstkreuz mit Stern der Bundesrepublik Deutschland (Great German Cross of Merit, with Star) and the Verdienstorden des Landes Berlin (Berlin Order of Merit).

Invited by Walter Fink, he was the seventh composer featured in the annual Komponistenporträt of the Rheingau Musik Festival in 1997, in songs and chamber music with the Auryn Quartet, playing the piano himself.

His commissioned work, Cantus for Clarinet and Orchestra, dedicated to the clarinetist and composer Jörg Widmann, was premiered on January 13, 2006, in the WDR's Large Broadcasting Hall in Cologne, Germany, in the presence of the composer, who claims the work was inspired by Claude Debussy's compositions for clarinet.

His opera Medea after Franz Grillparzer was premiered at the Vienna State Opera in 2010, conducted by Michael Boder, with Marlis Petersen in the title role.

In 2011 he was awarded the Ernst von Siemens Music Prize "für sein Lebenswerk" (for his life's work).[