Robert Terwilliger Sr.

"Robert was a peaceful boy, sickly and weak from a congenital heart defect. But then that Simpson boy started tormenting him, and he he crossed over into dementia."

- Mr. Terwilliger lies about his son on trial

Robert Terwilliger Sr. is the minor antagonist for 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 Terwilliger and a grandson named Gino Terwilliger.

He is voiced by John Mahoney.

History
When Sideshow Bob was put on trail 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.

Trivia

 * He is voiced by John Mahoney who played Kelsey Grammar (Sideshow Bob) and David Hyde Pierce's (Cecil Terwilliger) father in Frasier.
 * Sideshow Bob gets his look from his father, including face shape, pale skin and long foots. His hair, however, comes from his mother.