6. Johnny Cash
On 1955's "Folsom Prison Blues," Johnny Cash sang, "I shot a man in Reno just to watch him die." Those were bold lines for Eisenhower-era America, but Cash was just starting to break the rules. He played country songs that appealed to rock fans. He made a movie about Jesus, featuring his wife June Carter Cash playing the role of Mary Magdalene. (Few biblical scholars knew that Mary spoke with a Southern accent.) The man consumed enough prescription drugs to make Rush Limbaugh blush, and passionately defended Bob Dylan when the folkies said he sold out. He was a man of contradictions and the only country singer of all time who could credibly cover Soundgarden's "Rusty Cage," Nine Inch Nails' "Hurt" and Depeche Mode's "Personal Jesus."