Michael Tilson Thomas (born December 21, 1944), nicknamed MTT, is an American conductor, pianist and composer. He is the son of Broadway stage manager Ted Thomas , and the grandson of noted Yiddish theater stars Boris and Bessie Thomashefsky.

He was born in Los Angeles, California, where he studied at the University of Southern California under Ingolf Dahl among others. In 1969 he made his conducting debut with the Boston Symphony Orchestra, replacing an unwell William Steinberg in mid-concert. He stayed with the Boston ensemble as an assistant conductor until 1974. He was music director of the Buffalo Philharmonic Orchestra from 1971 to 1979, and from 1971 to 1977 conducted the series of Young People's Concerts with the New York Philharmonic.

From 1981 to 1985 he was principal guest conductor of the Los Angeles Philharmonic Orchestra, and from 1988 to 1995 he was principal conductor of the London Symphony Orchestra, becoming principal guest conductor thereafter. In 1995 he became music director of the San Francisco Symphony. He is founder of the New World Symphony Orchestra (based in Miami, Florida) which acts as a training ground for young musicians.

Tilson Thomas has conducted a wide variety of music, and is a particular champion of modern American works, recording the complete symphonies of Charles Ives and the premiere recording of Steve Reich's The Desert Music. His compositions include From the Diary of Anne Frank; Shówa/Shoáh, memorializing the fiftieth anniversary of the bombing of Hiroshima; Poems of Emily Dickinson; and Urban Legend.

He is currently (January 2005) preparing for the April 2005 Carnegie Hall premiere of Remembrances of Thomashefsky's Yiddish Theater.