George Allen Russell (June 23, 1923 – July 27, 2009) was an American jazz pianist, composer, arranger and theorist. He is considered one of the first jazz musicians to contribute to general music theory with a theory of harmony based on jazz rather than European music, in his book Lydian Chromatic Concept of Tonal Organization (1953).

Russell was born in Cincinnati, Ohio, on June 23, 1923, to a white father and a black mother. He was adopted by a nurse and a chef on the B & O Railroad, Bessie and Joseph Russell. Young Russell sang in the choir of the African Methodist Episcopal Church and listened to the Kentucky Riverboat music of Fate Marable. He made his stage debut at age seven, singing "Moon Over Miami" with Fats Waller.

Surrounded by the music of the black church and the big bands which played on the Ohio Riverboats, and with a father who was a music educator at Oberlin College, he began playing drums with the Boy Scouts and Bugle Corps, receiving a scholarship to Wilberforce University, where he joined the Collegians, a band noted as a breeding ground for jazz musicians including Ben Webster, Coleman Hawkins, Charles Freeman Lee, Frank Foster, and Benny Carter. Russell served in that band at the same time as another noted jazz composer, Ernie Wilkins. When called up for the draft at the beginning of World War II, he was hospitalized with tuberculosis, during which he was taught the fundamentals of music theory by a fellow patient.

After his release from the hospital, he played drums with Benny Carter's band, but decided to give up drumming as a vocation after hearing Max Roach, who replaced him in the orchestra. Inspired by hearing Thelonious Monk's "'Round Midnight", Russell moved to New York in the early 1940s, where he became a member of a coterie of young innovators who frequented the apartment of Gil Evans on 14 West 55th Street, a clique which included Miles Davis, Charlie Parker, Gerry Mulligan, and John Lewis, later the music director of the Modern Jazz Quartet.

In 1945–46, Russell was again hospitalized for tuberculosis for 16 months. Forced to turn down work as Charlie Parker's drummer, during that time he worked out the basic tenets of what was to become his Lydian Chromatic Concept of Tonal Organization, a theory encompassing all of equal-tempered music which has been influential well beyond the boundaries of jazz. During this period he also studied composition with Stefan Wolpe. The first edition of his book was published by Russell in 1953, while he worked as a salesclerk at Macy's. At that time, Russell's ideas were a crucial step into the modal music of John Coltrane and Miles Davis on his classic recording, Kind of Blue, and served as a beacon for other modernists such as Eric Dolphy and Art Farmer.

While working on the theory, Russell was also applying its principles to composition. His first famous composition was for the Dizzy Gillespie Orchestra, the two-part "Cubano Be, Cubano Bop" (1947), part of that band's pioneering experiments in fusing bebop and Cuban jazz elements. "A Bird in Igor's Yard" (a tribute to both Charlie Parker and Igor Stravinsky) was recorded in a session led by Buddy DeFranco the next year. Also, a lesser known but pivotal work arranged by Russell was recorded in January 1950 by Artie Shaw entitled "Similau" that employed techniques of both the works done for Gillespie and DeFranco.

Russell began playing piano, leading a series of groups which included Bill Evans, Art Farmer, Hal McKusick, Barry Galbraith, Milt Hinton, Paul Motian, and others. Jazz Workshop was his first album as leader, and one where he played relatively little, as opposed to masterminding the events (rather like his colleague Gil Evans).

In 1957, Russell was one of several composers commissioned by Brandeis University to write a piece for their jazz festival. He wrote a suite for orchestra, All About Rosie, which featured Bill Evans among other soloists, and has been cited as one of the few convincing examples of composed polyphony in jazz.