...with the monsters of the D&D game, so here are some links to help out!
Illithid (Mind Flayer) - actually an unnamed race in my games, though many just call them "squid heads" or "brain eaters". Ancient alien species that have incredible mental powers, and consider most other species food...just food...or slaves....actually....
Amusing Illithid Toon
Neogi - Nasty little buggers. About the size of a small dog, but always accompanied by much tougher brutes who do the killing for them. Venomous and not without their own mental powers, these horrors are consumate slavers and psychopaths...not nice!