Cthulhu, fictional entity created by fantasy-horror writer H.P. Lovecraft and introduced in his story ‘The Call of Cthulhu,’ first published in the magazine Weird Tales in 1928. The creature is described as having ‘an octopus-like head whose face was a mass of feelers.’ It destroys the sanity of those who see it.
Lovecraft's Cthulhu and the Great Old Ones: Fact, Fiction or Foretold in the Necronomicon?
Cthulhu Cthulhu, Mythological creatures, Mythical monsters
S. Petersen's Field Guide to Cthulhu Monsters, The H.P. Lovecraft Wiki
What is your favorite depiction of Cthulhu? - Quora
H.P. Lovecraft: The Cthulhu Myth Explained, Audible UK
H.P. Lovecraft and the Cthulhu Mythos
Cthulhu - Wikipedia
More on the Nature of Cthulhu and its Spawn
Hastur, The H.P. Lovecraft Wiki
Cthulhu Mythos species - Wikipedia