Billy Strayhorn joined Duke Ellingtons band in 1939 as a lyricist, but his duties instantly increased to handling arrangements, songwriting and piano playing. He even composed Take the A-Train, which became the Dukes theme soon after. The musical link between Strayhorn and Ellington was so strong that it's hard to tell where one contribution began and the other ended (they quickly adopted each others styles, and the writing credits arent always correct). Together, they were an unbeatable team, and though Ellington guarded Strayhorn from working outside his stable of artists on a continual basis, he did manage to break away occasionally. His song Lush Life was first recorded by Nat Cole, and is one of the finest torch songs ever written.