An illithid, also called a mind flayer, was an evil and sadistic being, humanoid in appearance, but with a four-tentacled octopus-like head. These beings were feared throughout the Underdark for their telepathic abilities and usually were not without two or more slaves, mentally bound to each individual mind flayer. Although they cooperated to achieve a goal, they would back away at the first sign that something was not profitable to themselves. They were capable of speaking Undercommon, but preferred telepathic communication and would attempt to mentally dominate any non-slave, non-illithid they met. They fed on the brains of sentient creatures and were thus feared. Their natural psionic abilities also made them respected in the eyes of the drow, beholders, duergar, and the other dominant races of the Underdark.