|“||Robert was a peaceful boy, sickly and weak from a congenital heart defect. But then that Simpson boy started tormenting him, and he crossed over into dementia.||„|
|~ Mr. Terwilliger lying about his son on trial.|
Robert Terwilliger Sr. is a supporting antagonist in The Simpsons episode "Funeral for a Fiend". He is a husband of Dame Judith Underdunk and the father of Sideshow Bob and Cecil Terwilliger. He has a daughter-in-law named Francesca and a grandson named Gino.
He was voiced by the late John Mahoney, who also played Sideshow Bob and Cecil Terwillinger.
When Sideshow Bob was put on trial for trying to kill the Simpson family, his father who is a doctor claims Bart had taunted Bob so much it had caused him mental problems. This witness, followed by Bob's heartbreaking scene, eventually led everyone in the courtroom to believe it is all Bart's fault Bob is trying to kill him repeatedly. When Bart threw Bob's medication out of a window (believing it to be a biological weapon), it caused Bob to "die". In reality, Bob's father, bending above his lying son, injected him with a death simulation drug. This helped Bob to avoid the trial and conduct a complex plan to kill Bart Simpson by locking him in Bob's coffin and cremating him. However, this process was stopped by Lisa on time and Bob with his entire family ended up in prison.
- So far, Robert has only appeared once in the show and has never returned in any episodes including his son Bob, much like the rest of the Terwilliger Family. As of now, it's hihgly unlikely that Robert will ever make any more appearances in the show due John Mahoney's death in 2018.