For too long, jazz composer and pianist Billy Strayhorn was thought of as a mere understudy or, at best, a collaborator of the great Duke Ellington. But as jazz musicians and historians continued to delve into Strayhorn's work, it became clear that not only was the artist's output equal to Ellington's in its brilliance, but his musical ideas had a profound impact on Ellington himself. Strayhorn, who was one of the few openly gay figures in jazz history, has written some of the genre's most lasting compositions, including "Take the 'A' Train" (the Ellington band's theme song), "Satin Doll," and his masterpiece, "Lush Life," one of the most frequently covered pop songs ever written. Strayhorn died of throat cancer in 1967 at the age of 54.