The composer of the song 'Over the Rainbow' is Harold ARLEN, a five-letter name. ARLEN was an American composer of popular music who wrote over 500 songs for Broadway and Hollywood films. He is best known for his collaborations with lyricist Yip Harburg, including the classic song 'Over the Rainbow'. The song was written for the 1939 film The Wizard of Oz and won the Academy Award for Best Original Song.