Mind Flayers seem to look a whole lot like Cthulhu. Is there any relationship/inspiration between the two?
\$\begingroup\$ @ThomasMarkov I'll suggest reading this meta regarding this question type and that close reason. \$\endgroup\$– Someone_Evil ♦Feb 15, 2021 at 9:50
Indirectly, yes. Gary Gygax tells us that "the mind flayer I made up out of whole cloth using my imagination, but inspired by the cover of Brian Lumley's novel in paperback edition, The Burrowers Beneath." Said novel was firmly rooted in the Cthulhu mythos; in fact, Lovecraft's character Robert Harrison Blake wrote a short story titled "The Burrower Beneath." We may suspect that title was an influence on Brian Lumley's choice of titles.
The cover in question, for reference:
20\$\begingroup\$ Interestingly, Lovecraft actually got the title from Robert Bloch, the writer of Psycho, who sent H.P.L. a draft of a story called "The Blasphemy Beneath". Lovecraft in turn used "The Burrower Beneath" as a title for one of Robert Blake's stories because the fictional Blake was a sort of tribute to the actual Bloch. Bloch returned the favor by making a nameless, Lovecraft-inspired character the protagonist of his own story "The Shambler from the Stars" (itself a title derived from one of Blake's fictional books). \$\endgroup\$ Sep 9, 2010 at 21:02
5\$\begingroup\$ This is interesting. As a minor point: that creature will actually be a Chthonian, who is part of the Mythos, but is significantly different from Cthulhu. So the full answer would seem to be: Mind Flayers are inspired by the Cthulhu Mythos, but not by Cthulhu himself. \$\endgroup\$– GrahamOct 25, 2010 at 11:58
1\$\begingroup\$ @Graham Although chthonians are pretty much big worms with tentacles at one end, so mind flayers look a lot more like Cthulhu than like chthonians. \$\endgroup\$ Nov 30, 2017 at 22:59
As Graham points out the illithids share more physical similarity to Chthonians.
Chthonians (/ˈθoʊniənz/ from Greek: chthon, "earth") are fictional creatures in the Cthulhu Mythos. Chthonians as name of the species is the creation of English horror-fiction writer Brian Lumley and was first featured in his short story "Cement Surroundings" (1969)—though the creature never made a direct appearance. The chthonians had a more prominent role in Lumley's novel The Burrowers Beneath (1974), whose title was taken from one of the stories said to have been written by Robert Blake in Lovecraft's "The Haunter of the Dark."
The brain sucking probably refers to "The Space-Eaters" by Frank Belknap Long.
I think they were definitely inspired by Cthulhu, and there's no secret that the original D&D designers and fans were very familiar with the works of HP Lovecraft. It's probably not just illithids, either. We could look closely and see a lot Mythos-inspired monsters in the earliest monster manuals as well as the newest ones.
The Cthulhu Mythos was featured in the original print-runs of Deities and Demigods.