The mind flayers are typically purple or gray humanoids with tentacles for lower parts of their face. Easily confused with Cthulhu, who is more commonly depicted as having green skin and being of colossal size, unlike mind flayers who are human sized. Mind flayers are also a species of several individuals, where as Cthulhu is a singular being. Mind flayers use their tentacles to eat the minds of sentient beings.

Description from Forgotten Realms wiki

Mind flayers, also known as illithids, and sometimes referred to as ghaik by the githyanki, were sadistic aberrations feared by sentient creatures on many worlds across the multiverse due to their powerful psionic abilities. From their twisted lairs deep in the Underdark, these alien entities sought to expand their dominion over all other lifeforms, controlling their minds to use them as obedient thralls. They consumed their victims' very personality by extracting and devouring their brains while they were still alive.

See also

• dungeons_and_dragons
• forgotten_realms
• mind_wipe