Bill Fitch (born 1935) is an NBA coach who has been successful in making teams playoff contenders throughout his coaching career.

Fitch was a US Marine as a youngster, a fact that Larry Bird credited in his book Driven as an important reason for his strong work ethic.

During his 25-year coaching career, Fitch repeatedly worked to turn around failing teams. As of 2004, Fitch ranked fifth among all NBA coaches in all-time number of victories (with 944), but also ranked second in all-time losses (with 1106). He has been named NBA coach of the year two times, and he guided Bird, Kevin McHale, Robert Parish and the rest of the Boston Celtics to the 1981 NBA world championship, defeating the Houston Rockets 4 games to 2 in the finals. Fitch actually went on to coach the Rockets, where he led a team featuring Hakeem Olajuwon and Ralph Sampson to the 1986 NBA Finals, where they were ironically defeated once again by Bird's Celtics 4 games to 2 for the world championship.

He has also coached the Cleveland Cavaliers, New Jersey Nets and Los Angeles Clippers.