arranger

In music, a person who adapts or assists in orchestrating the music of another composer at the composer's request. The use of an arranger became established in Hollywood; Sergei Rachmaninov, George Gershwin, and Leonard Bernstein, among others, composed concert works employing such assistance.

Arrangers are also common in jazz: the more notable examples include Gil Evans (1912–1988), who arranged music for Miles Davis and others; and Billy Strayhorn (1915–1967) for Duke Ellington. Composers of unauthorized arrangements include Johann Sebastian Bach (Vivaldi), Mozart (Handel's Messiah), and Stravinsky (Tchaikovsky and Pergolesi).