H.P. Lovecraft and a very kaiju-esque Cthulhu from Giga by Yuji Kaida, 1989.
Cthulhu’s origin is typically mysterious for a creature that is older than the earth but appears he was one of the Great Old Ones, a collection of god like beings that roamed the universe.
Cthulhu settled on earth and was imprisoned beneath the oceans in his sunken city of R’lyeh. The first appearance of the Cthulhu was in the short story “The Call of Cthulhu” published in Weird Tales in 1928.
Ph’nglui mglw’nafh Cthulhu R’lyeh wgah’nagl fhtagn!