Sideshow Bob.

About Sideshow Bob

Dr. Robert Underdunk "Bob" Terwilliger Jr., PhD, better known as Sideshow Bob, is a recurring antagonist in the animated television series The Simpsons. He is voiced by Kelsey Grammer and first appeared in the episode "The Telltale Head". A self-proclaimed genius and graduate of Yale University, Bob champions high culture and speaks with a transatlantic accent similar to the one Grammer uses as Dr. Frasier Crane in the sitcoms Cheers and Frasier. He began his career as a sidekick on Krusty the Clown's television show, but after enduring constant abuse, Bob framed his employer for armed robbery in "Krusty Gets Busted", only to be foiled by Bart Simpson and sent to prison. After Bart exposes him, Bob begins seeking revenge, and the two become archenemies.