7. Ash (Alien)
I present to you the real villain of Alien, Ash, a cybernetic life form, but an utterly callous foe all the same. He's fully responsible for allowing quarantine to be broken towards the beginning of the film that allows for the impregnated Kane to get back on board the ship, exposing everyone to certain death later on. For the entire film he proves himself a master manipulator, always protecting the company's vested interest in the safe return of the alien organism, and so it's only appropriate he gets it in the head towards the final act of the film. By the time Ripley throws him up against the wall you're all but begging for this prick to face the music. After he almost rapes Ripley with a magazine, in comes Parker and Lambert (crying as usual), to save the day. Once his head gets knocked off via the gas tank canister, it's a more than fitting end to the bloodshed he caused the crew of the Nostromo. And even after all that, he still gets a needed burst of flames to his milky head just to seal the deal on one of the more satisfying villain deaths in cinema history...