Cthulhu has been involved in Simpsons through the comic and show.
Cthulhu has been seen in the Simpsons strictly in the Treehouse of Horror genre.
Cthulhu was in the Treehouse of Horror XXIV opening (see video). He was seen while Bart was skateboarding home. His tentacles created a pathway for Bart's journey home. He hasn't been seen on the show since.
Cthulhu was also apart of the The Simpsons' Treehouse of Horror #19. In the story Skinner has had enough of Bart and tells him and Milhouse to clean up the school's old library. While Milhouse gets to work Bart looks for something interesting. He soon finds the necronomicon. They then use the old books to build a staircase to escape through through a school window. They go home and Bart realises that the necronomicon is the book of the dead and tells the history of the monster gods called the called the great old ones. The book also shows them how to summon them and make them do their bidding. Bart decides to summon Cthulu to get revenge on Skinner. At first nothing happens, but slowly as they walk around town tentacles appear and kill and muilate people. These included Jimbo, Kearny and Dolph. They discover that they really did summon Cthulu and decide to make Cthulu attack Skinner. Cthulu attacks Skinner at Bart's will. But soon Cthulu was out of control and was attacking everyone on sight! Bart and Milhouse go home to try and figure out how to get rid of Cthulu using the Necronomicon. Santa's Little Helper got the book first and transforms into a hell dog then a squid like monster. Bart can't find the answers in the book and suddenly a tentacle knocks him out. He wakes up and goes down for breakfast and finds that everyone has been turned into a minion of Cthulu and possess many squid like traits. They are also eating Milhouse for breakfast.
- Episode – "Treehouse of Horror XXIV"
- Episode – "Diggs" (name seen)
- Comic book – Treehouse of Horror #19
- Video game – Tapped Out
- Episode – "Halloween of Horror"