HADES

Even though he's fully sentient, HADES has little in the way of personality, only existing to carry out his sole function of exterminating all life on Earth. What level of cunning and deceit he does display turn out to be on the advice of Sylens. If anything, this makes it more horrific; it can't be reasoned with, only bound or destroyed and it gives it an eldritch Lovecraftian quality.

Example of:
Generic Doomsday Villain