There were many movies that were made based on the changes in Cthulhu's mythological system. The following are some of the more well-known works: 1 The Call of Cthulhu: The first novel in the Cthulhu Mythological Series, co-written by HP Lovecraft and Robert E Howard, was first adapted into a movie in 1978. 2 The Cthulhu Mythos: The New Horizon: The first Cthulhu Mythological novel by HP Lovecraft and Robert E Howard was first adapted into a movie in 1971. 3 The Cthulhu Mythos: The dark visions of l'Vladimir: The second novel in the Cthulhu mythological series written by HP Lovecraft and Robert E Howard was first adapted into a movie in 1974. 4 The Cthulhu Mythos (A Panties and Mirror): The third step of the Cthulhu Mythological novel series written by HP Lovecraft and Robert E Howard was first adapted into a movie in 1972. 5 The Cthulhu Mythos: The Return of Cthulhu: The fourth step of the Cthulhu Mythological novel series written by HP Lovecraft and Robert E Howard was first adapted into a movie in 1979. 6 The Cthulhu Mythos: The dark visions of l'Vladimir: The fifth step of the Cthulhu mythological novel series written by HP Lovecraft and Robert E Howard was first adapted into a movie in 1974. These were some of the more well-known movies adapted from the Cthulhu mythological system, and of course, there were many other excellent works.