Cthulhu is not part of any mythology. He is a fictional entity in the 1920's Horror literature of the author Howard Philips Lovecraft. He appears in only one of HP Lovecraft's stories, "The Call of Cthulhu". If you want to read more by the author, I would advise "Nyarlathotep", "The Color Out of Space, or "Herbert West, Re-Animator".
Cthulhu was created in 1928.
Cthulhu's Reign was created in 2010.
Acolytes of Cthulhu was created in 2001.
The Spawn of Cthulhu was created in 1971.
Crypt of Cthulhu ended in 2001.
Crypt of Cthulhu was created in 1981.
Pimoa cthulhu was created in 1994.
Cthulhu Cultus ended in 2001.
The Mask of Cthulhu was created in 1958.
The Trail of Cthulhu was created in 1962.
Cthulhu's Reign has 309 pages.
The Mask of Cthulhu has 201 pages.