Robert Terwilliger, Sr.

Dr. Robert Terwilliger, Sr. is Sideshow Bob's father.

When Sideshow Bob was put on trial for trying to kill The Simpsons, he claimed that Bob had suffered from an illness caused by his desire to kill Bart Simpson. Bart threw Sideshow Bob's medication out of a window (believing it to be a biological weapon). This subsequently caused Sideshow Bob to "die". In reality, Bob was injected with a death simulation drug by his father prior to the fated trial in order to conduct a complex plan to kill Bart Simpson via locking him in a coffin and cremating him. He, and the rest of the Terwilliger family, are in prison.

Behind the Laughter

 * Robert Terwilliger, Sr. was voiced by the late John Mahoney, who also plays the father of brothers Frasier and Niles Crane in Frasier, which were voiced by Kelsey Grammer and David Hyde Pierce, the voice actors of Sideshow Bob and his brother Cecil on The Simpsons.