Illithids

Mind-Flayers, also known as Illithids, are a malevolent and cruel race of monsters with psionic powers from the Dungeons & Dragons roleplaying fantasy game. They are, alongside the Beholder, one of the game's most classic and recognizable creatures.

Description
Illithids are humanoid aberrations with an octopus or squid-like shaped head. They have a circle-shaped mouth full of sharp fangs which allows them to feast on the brains of other creatures. They are hermaphroditic and reproduce by spawning a mass of larvae two or three times in their life. The larvae resemble miniature illithid heads or four-tentacled tadpoles. Larvae are left to develop in the pool of the Elder Brain. The ones that survive after 10 years are inserted into the brain of a sapient creature, which the larvae then consumes, causing it to absorb the host's physical form and achieve sapience. This process is called ceremorphosis. Illithids often experiment with non-humanoid hosts, but ceremorphosis involving other creatures usually fails, killing both host and larva. There is a variant of this process involving adult Mind-Flayers called laceremorphosis, which makes them bigger, stronger and more powerful than regular mind flayers. They become Ulitharid or illithid-nobles, and posses six face tentacles instead of the regular four.

Society and Culture
Mind Flayers are very sadistic and mean-hearted beings, and believe themselves to be superior to other species in the game's Multiverse, which makes them tipically enslave other races they perceive as weak. They tipically make their homes in the dark caverns of the Underdark, the same place where other villainous beings such as Drows and Driders are often found. Mind flayer communities range in size from two hundred to two thousand, and that is counting only the illithids. Each mind flayer in the community likely has at least two slaves to do its bidding. In these communities, the number of slaves often far outstrips the number of mind flayers. For example, the illithid city of Oryndoll has a total population of 26,000, but mind flayers only account for 3,450 of that number.