Jack White as a karate-wielding Elvis. Paul Rudd as John Lennon. John C. Reilly as a Johnny Cash/Brian Wilson hybrid of fictional blues legend Dewey Cox. And, um, Jewel. Behold the trailer for Judd Apatow's ('Knocked Up') music biopic spoof, 'Walk Hard' -- inspired by 'Ray' and 'Walk the Line' -- due in theaters on Dec. 21.