"The Understudy" is the fifth episode of British dark comedy anthology series Inside No. 9. It was first broadcast on 5 March 2014 on BBC Two. The episode was written by and starred Steve Pemberton and Reece Shearsmith, and guest-starred Lyndsey Marshal, Julia Davis, Rosie Cavaliero, Roger Sloman, Di Botcher, Richard Cordery, Bruce Mackinnon and Jo Stone-Fewings. Pemberton plays actor Tony, who is starring as Macbeth in a West End production of Shakespeare's Macbeth, and Shearsmith plays Jim, Tony's understudy. The plot of "The Understudy" partially mirrors the story of Macbeth, exploring the theme of power and the lives of actors.