Dr. Robert Underdunk Terwilliger, PhD, better known as Sideshow Bob, is a recurring character in the animated television seriesThe Simpsons. He is voiced by Kelsey Grammer and first appeared briefly in the episode "The Telltale Head." Bob is a self-proclaimed genius who is a graduate of Yale University, a member of the Republican Party, and a champion of high culture. He began his career as a sidekick on Krusty the Clown's television show, but after enduring constant abuse, Bob attempted to frame his employer for armed robbery in "Krusty Gets Busted." The plan was foiled by Bart Simpson, and Sideshow Bob was sent to prison.
Bob made his second major appearance in season three's "Black Widower"; the writers echoed the premise of the Coyote chasing the Road Runner by having Bob unexpectedly insert himself into Bart's life and attempt to kill him. In each appearance thereafter, Bob has assumed the role on The Simpsons of an evil genius. Episodes in which he is a central character typically involve Sideshow Bob being released from prison and executing an elaborate revenge plan, usually foiled by Bart and Lisa. His plans often involve murder and destruction, usually targeted at Bart or, less often, Krusty, though these plans often involve targeting the entire Simpson family.
Sideshow Bob shares some personality traits of Grammer's character Frasier Crane from the sitcoms Cheers and Frasier, and has been described as "Frasier pickled in arsenic". Several parallels have been explicitly drawn in The Simpsons between Bob and Frasier Crane – Bob's brother Cecil and his father were played by David Hyde Pierce and John Mahoney respectively, echoing the roles they played in Frasier. Grammer, who based Bob's voice on that of actor Ellis Rabb, has been praised for his portrayals of the character. In 2006, he won an Emmy for Outstanding Voice-Over Performance for his work in the episode "The Italian Bob."
As of 2014, Bob has had speaking appearances in 15 episodes and been featured in 13; the most recent of the latter, "Clown in the Dumps," aired during the 26th season. In addition to his recurring role in the series, Sideshow Bob has made several appearances in other Simpsons media. He appears in the Simpsons Comics, cameos in the 2007 video game The Simpsons Game, and stars as the main antagonist in The Simpsons Ride at Universal Studios' theme parks. Sideshow Bob is also known for his singing voice; several of Grammer's performances have been included in The Simpsons musical compilations.