I give you the write-up on mind-flayers:
Mind flayers, also known as illithids, meaning "mind flayers" or "mind rulers" in Undercommon, and sometimes referred to as ghaik by the githyanki, were evil and sadistic aberrations, feared by sentient creatures on many worlds across the multiverse due to their powerful innate psionic abilities.Dwellers of deep Underdark areas, these alien humanoid-looking beings sought to expand their dominion over all other creatures, controlling their minds to use them as hopeless slaves and devouring their brains for sustenance.
Not creatures to invite to adventure with. And please don't suggest they be romanced.
