Mind flayers, also called illithids, are the scourge of sentient creatures across countless worlds. Four tentacles snake from their octopus-like heads, flexing in hungry anticipation when thinking creatures come near.
In eons past, illithids controlled empires that spanned the planes. They subjugated and consequently warped whole races of humanoid slaves, including the githyanki and githzerai, the grimlocks, and the kuo-toa. Conjoined by a collective consciousness, the illithids hatch plots as far-reaching and evil as their fathomless minds can conceive.
Since the fall of their empires, illithid collectives on the Material Plane have resided in deep in the Underdark.