15 Films Defined by Songs of a Single Artist

 Christina Aguilera's new movie, 'Burlesque,' continues a long tradition, from 'Jailhouse Rock' to 'Purple Rain' to 'The Bodyguard,' of singers starring in films for which they also dominate the soundtrack. Which got us thinking about singers who have defined the sound and spirit of an entire film without ever appearing onscreen. Here are 15 of our favorite examples of singers whose voices alone are like an uncredited main character.