Dr. Robert "Bob" Underdunk Terwilliger, Jr., better known by his stage name, Sideshow Bob, is both a recurring character and the secondary antagonist of The Simpsons. He got his stage name when he was Krusty the Clown's sidekick. Bob is a self-proclaimed genius, member of the Republican Party, champion of high culture, former children's entertainer-turned-criminal mastermind and Bart Simpson's nemesis. He loves Gilbert and Sullivan operettas and is known for his gigantic feet, which have gotten him into trouble on more than one occasion.