Sideshow Bob (aka Robert Underdunk Terwilliger)
Currently residing in Springfield Penitentiary, where he has dreamed of revenge, hatched many evil schemes, and staged a production of "Evita".
First Appearance: February 25, 1990, "The Telltale Head".
The Scoop: Originally a silent and nondescript background character, he didn't become an evil genius until the "Krusty Gets Busted" episode at the end of the first season.
How about a wikia about Sideshow's father Robert Terwilliger Sr.
"Writing for Kelsey is great," says executive producer George Mayer. "He can give the kind of purple, florid, melodramatic speeches that most of our characters would never give. And he can sing."
Artist and creator Matt Groening: "Sideshow Bob is a man of great education and culture, but he is still consumed with the most bizarre, arbitrary hatred of Krusty and Bart. Every time he gets out of jail, he goes after the same people, over and over. You'd think he would be smarter than that, but no."
From TV Guide Oct, 2000