 Grammer had been the voice of Sideshow Bob on "The Simpsons" since 1990.In a 1997 episode (while "Frasier" was still in production), the character's brother, Cecil Terwilliger, was introduced, played by Pierce, as referenced in the episode title, "Brother from Another Series".The episode contained numerous "Frasier" references, including a "Frasier"-style version of "The Simpsons" theme for a transition and its iconic title card for the same thing.