Terrence Mitchell Riley (born June 24, 1935) is an American composer and performing musician best known as a pioneer of the minimalist school of composition. Influenced by jazz and Indian classical music, his music became notable for its innovative use of repetition, tape musictechniques, and delay systems.

Riley is best known for his 1964 composition In C and 1969 album A Rainbow in Curved Air, both considered landmarks of minimalism and important influences on experimental, rock, and electronic music. Since the 1970s, he has collaborated extensively with chamber ensemble the Kronos Quartet. Born in Colfax, California in 1935, Riley began performing as a solo pianist during the 1950s. During that decade, he studied composition at San Francisco State University, the San Francisco Conservatory, and University of California, Berkeley, studying with Seymour Shifrin and Robert Erickson. He was involved in the experimental San Francisco Tape Music Center, working with Morton Subotnick, Steve Reich, Pauline Oliveros, and Ramon Sender. Throughout the 1960s he also traveled frequently in Europe, taking in musical influences and supporting himself by playing in piano bars.

His most influential teacher was Pandit Pran Nath (1918–1996), a master of Indian classical voice who also taught La Monte Young, Marian Zazeela, and Michael Harrison. Riley made numerous trips to India over the course of their association to study and accompany him on tabla, tambura, and voice. In 1971 he joined the Mills College faculty to teach Indian classical music. Riley also cites John Cage and “the really great chamber musicgroups of John Coltrane and Miles Davis, Charles Mingus, Bill Evans, and Gil Evans” as influences on his work. He was awarded an Honorary Doctorate Degree in Music at Chapman University in 2007.