Harold Arlen was often billed as "the Composer of 'Over The Rainbow.'" By the time he was working on Wizard of Oz in 1938, Arlen and lyricist Ted Koehler had more than a decade of songwriting successes with hits like “Get Happy” “Stormy Weather” and “Ill Wind.” But when writing "Over the Rainbow,” Arlen didn’t know it would become, possibly, the most famous song of all time.