A mindslayer is a mythical creature of the evil Mindflayers. It is an alien slug-beast (cthulhoid meets Hutt) that the mindflayers have many myths about. It is blind and uses psionic powers to see. They have the ability to be a slaver by implanting a worm-like creatures in their victims. They evolved from blind, slugs that were highly telepathic.
Rough sketch of a Mindslayer