Illithid: mind flayer in Underdark

I recently read the book "Exile" by R. Salvatore and was impressed by the illithids and their culture!

The Illithids are a race of creatures similar to Lovecraft's Cthulhu, but unlike this ancient god - these creatures are many, they live in large cities and they have a very developed society. Illithids are diviners, mind flayers. They have strong telepathic abilities, they are able to subjugate and control other people's minds to their will and keep them under control for a very long time.