Kelsey Grammer explained the origins of the low, melodious voice of Sideshow Bob and explained how singing Tony Bennett songs on the set of Cheers earned him the role as the beloved Simpsons villain.
During an interview on the BBC's The Graham Norton Show, Grammer explained that he was offered the role of Sideshow Bob through Sam Simon, the late Simpsons co-creator, and a former writer and producer for Cheers. When The Simpsons staff decided to give Sideshow Bob a voice (he'd previously been seen as Krusty the Clown's sidekick, but not heard), Simon recalled Grammer's Bennett-esque belting and offered him the role, since it required a performance of Cole Porter's "Ev'ry Time We Say Goodbye." Grammer agreed, and after reading the script, realized a voice based on famed theater actor Ellis Rabb was perfect for the pompous Sideshow Bob.
"When I was working for [Rabb], I was painting his bathroom and hanging wallpaper and stuff like that — I wasn't really a successful actor at the time," Grammer recalled, before easing into Sideshow Bob's familiar voice. "But Ellis would regale me with stories when he came home from work, and he would say things like this: 'Ohh, Kelsey, that baby should have been mine.' And I thought, 'This guy — I'm gonna use him someday.' And when I read the script for Sideshow Bob, I said, 'This is Ellis Rabb,' and I went immediately into, "Ohh Bart, I just despise you.'"