Leonide Massine (1895-1979) was trained at the Imperial School in Moscow and choreographed for Diaghilev's company from 1915 to 1928.
Like Fokine, he later emigrated to the United States and choreographed for the Ballet Russe de Monte Carlo and American Ballet Theatre.
Among the more interesting of Massine's experiments were ballets to symphonic music, most notably Choreartium, done to Brahms's Fourth Symphony. Opinions differ as to whether the result was a success, but his use of Brahms instead of (say) Minkus is one indication of the way ballet has changed in this century.