Cecil Terwilliger (David Hyde Pierce) appears twice on the television series The Simpsons . He is Sideshow Bob (Kelsey Grammer)'s brother, but they fell out a long time ago when Cecil auditioned unsuccessfully for The Krusty Show, only to lose the part of Sideshow to Bob. When Bob is on work release from prison, he works for Cecil, but it turns out Cecil is just as insane as his brother, and he tries to blow up Bob and Bart in a city dam. Over 10 years later, Cecil returns and helps Sideshow Bob attempt to kill Bart. However, their plan fails and they are all taken to prison.