Bob’s transition into a speaking character occurred in the Season 1 episode where he framed Krusty for armed robbery to take over the show and transform it into an educational program. When Bart Simpson exposed his treachery, a decades-long rivalry was born, transforming Bob into Bart’s perennial nemesis. The Voice of a Villain: Kelsey Grammer’s Impact

He is the razor blade hidden inside a velvet glove. With his towering, thatch-roofed hair (a direct nod to the Brothers Grimm ), his bleeding-heart tattoo, and the voice that rolls like a Shakespearean actor savouring revenge, Bob represents something terrifyingly absent from Springfield: High-stakes, articulate malice.

Sideshow Bob, born Robert Underdunk Terwilliger Jr., is a genius-level intellect and a mastermind of evil schemes. He was a writer and director for Krusty the Clown's children's television show, "The Krusty the Clown Show," but his constant frustration and humiliation led to his downfall.

Robert Underdunk Terwilliger Jr. is not your typical cartoon antagonist. He is a man of contradictions: a criminal genius with a doctorate; a man obsessed with high culture who is trapped in a lowbrow world; and a character who elicits sympathy even as he plots grisly murder. He is, arguably, the most sophisticated satirical weapon in the show’s arsenal.