Stephen Michael Reich (born October 3, 1936) is an American composer who pioneered the style of minimalism. His innovations include using tape loops to create phasing patterns (examples are his early compositions, It's Gonna Rain and Come Out), and the use of simple, audible processes to explore musical concepts (for instance, Pendulum Music and Four Organs). These compositions, marked by their use of repetitive figures, slow harmonic rhythm and canons, have significantly influenced contemporary music, especially in the US. Reich's work took on a darker character in the 1980s with the introduction of historical themes as well as themes from his Jewish heritage. Different Trains (1988) has been called "the only adequate musical response—one of the few adequate artistic responses in any medium—to the Holocaust", and was credited with earning Reich a place among the great composers of the 20th century.

Reich's style of composition has influenced many other composers and musical groups, John Adams, the progressive rock band King Crimson, and the art-pop and electronic musician Brian Eno. Reich has been described by The Guardian as one of "a handful of living composers who can legitimately claim to have altered the direction of musical history",and the Village Voice's Kyle Gann has said Reich "may [...] be considered, by general acclamation, America's greatest living composer."On January 25, 2007, Reich was named the 2007 recipient of the Polar Music Prize, together with Sonny Rollins.