Monsterpiece Theater

Monsterpiece Theater is a recurring Sesame Street sketch hosted by Cookie Monster as Alistair Cookie. The sketch parodies the PBS series Masterpiece Theater, originally hosted by Alistair Cooke.

This segment has had at least three different openings, the first two of which specifically reflected the then-current Masterpiece Theater opens. On one early skit, "Me, Claudius", it featured no title card and opened on the camera panning across various statues before trucking over to Alistair Cookie as the Monsterpiece Theater opening theme music was heard. The first regular opening sequence had the title on a blue background, with a Union Jack flag as the P in "Monsterpiece". Most of these skits with this opening had Alistair Cookie with a pipe and then usually eating it at the end. Around Season 21, the library that Alistair Cookie was in was changed, and the pipe was dropped. In Season 23, this opening was replaced with a longer opening, which panned around a room, showing pictures and books referencing past segments. The opening theme music was also presented in its entirety. In Season 27, another new opening was produced with the title sliding in front of a computer-animated green curtain. Whenever a new opening was added, that opening would be used in all segments shown in those episodes, even if that particular segment was made years earlier. Skits that originally had Alistair Cookie's pipe had the opening and closing footage with Cookie re-taped, using the original 1980s voice recordings by Frank Oz.

Its successor is "Dinner Theatre", which premiered in Season 37.