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And now to kill you. There may be a slight ringing in your ears. Fortunately, you'll be nowhere near them.

Cecil Underdunk Terwilliger is the younger brother of Robert Terwilliger.


Cecil is the youngest member of the Terwilliger family (if you're not counting Gino or Neil).


Early life[]

When he was young, Cecil was ignored repeatedly by his parents, and instead compared to Bob, similar to the rest of his life.[1]

Cecil's dream since childhood was to become Krusty the Clown's sideshow on The Krusty the Clown Show, unaware as to how Krusty would treat him on the show. Cecil spent, according to Bob, "four years at clown college", to which Cecil replies, "I'd thank you not to refer to Princeton that way". Krusty and the producers of his show rejected Cecil during his audition, as they saw his performance failing. Cecil offered to perform his prepared "pie-in-the-face take" before he was ushered off-stage, but this did not change the producers' minds as Cecil lacked the dignity necessary to pull the bit off. It was then that Krusty spotted Robert, standing to the side in a fine suit and looking like he genuinely didn't want to be there. Krusty ordered a pie-in-the-face for him, the resulting impact knocking off Robert's top hat and causing his hair to spring up from beneath it, Krusty hired Robert as his sidekick on the spot. Cecil resented and became jealous of his brother. Despite that, he entered the hydroelectricity industry and "found his true calling" as a hydrodynamics engineer.

Springfield Dam Plot[]

When Sideshow Bob was released from prison, Cecil hired him to work for his company building a new hydroelectric dam along the river, proudly telling him that he was Springfield's "Chief Hydrological and Hydrodynamical Engineer". Cecil's true intentions, however, were to skim money from the dam project's contract, build a poor-quality dam, and frame his brother for the resulting destruction (mainly due to his still being sore about Sideshow Bob getting the part of sideshow on Krusty's show). Cecil's plot was discovered by Bart and Lisa Simpson, although they initially thought it was Sideshow Bob who was guilty until Cecil revealed his true colors. Ultimately, he lost the laundered money in a struggle against Bart. However, he does try to succeed in doing "the one thing Bob failed to do," which is, of course, killing Bart Simpson, albeit in an ironically crude fashion as him throwing Bart off of a cliff, although he hints that he will lie if anyone asks how he did it. This attempt was foiled, ironically by Sideshow Bob. Cecil wasn't done yet, however, so he planned to blow up the dam as well as directly kill Bart and Sideshow Bob by shooting the dynamite stick (Bob had to use the Dynamite as a rope to catch Bart), although Bob and Bart foiled this effort by cutting the detonation charge, nearly killing themselves in the process. Despite Bob's innocence, the brothers were sent to prison, since Chief Wiggum did not believe that Sideshow Bob was innocent, despite testimonies from Bart, Lisa, himself, and Lou.[2]

Faking Bob's death[]

Several years later, Cecil, alongside his father Robert Terwilliger Sr. and the rest of his family, conspired with Sideshow Bob to ensure he could kill Bart. To do this, they had Bob fake his death by placing a cocktail drug in him before a hearing, and then manipulate Bart into throwing away what seemed to be "medication" for a pre-existing condition. He was also briefly given parole to attend the "funeral." However, the Simpson family figured out Sideshow Bob's plan and stopped them, resulting in Cecil having an increased sentence. He was last seen playing cards with his father and nephew while Bob was having a breakdown.


  • Attempted mass-murder
  • Embezzlement
  • Faking a death


  • Kelsey Grammer, who voices Sideshow Bob, was also known for playing Dr. Frasier Crane. David Hyde Pierce, who voices his brother Cecil, also played his brother Dr. Niles Crane in the same show.
  • Their arguments in "Brother From Another Series" is a homage to the kinds of arguments the brothers would occasionally have.
  • It has been implied that Cecil has a degree of more intellect than Bob, as when he tried to throw Bart off the dam, he didn't fall for Bart's "crude for a genius like you" distraction, stating that he'll lie if anybody asked, while Bob would have fallen for Bart's distractions.[2]
  • His first name is pronounced "ses-ill", rather than “see-sill”, so as to be fancy.
  • He is hinted to be gay by calling Moe beautiful and making other "homosexual" remarks. Though despite this, his debut episode implies he may have been involved with a woman named Maris (an indirect reference to Niles' unseen first wife in the Frasier series) when Bart tried to distract him by blinding him from behind.
    • His more "homosexual" remarks may be an indirect reference to Cecil's actor, David Hyde Pierce, being homosexual in real life.


The full image gallery for Cecil Terwilliger may be viewed at Cecil Terwilliger/Gallery.


Terwilliger Family
Robert Terwilliger Sr. | Dame Judith Underdunk | Sideshow Bob | Cecil Terwilliger | Francesca Terwilliger | Gino Terwilliger