19. The Shark - Jaws
One of the few villains who is more terrifying when he's not seen - the shark in Jaws is most effective in the earlier parts of the film when he is an unknown quantity who has yet to be glimpsed by the audience. There is less fear when the shark actually appears thanks to the not entirely convincing mechanical shark used and the mystery is always less fun after its unveiling. The classic theme inspires dread upon the first note and the villain doesn't even need to show his face with the perfect example being the opening scene where a teenage girl is devoured by the shark and all we see and hear is some thrashing and screaming. Spielberg builds the suspense perfectly in that scene and the most chilling aspect is the fact that no enemy can be seen or heard.
18. HAL 9000 - 2001: A Space Odyssey
Played By: Douglas Rain In Stanley Kubrick's sci-fi masterpiece, HAL is the artificial intelligence that goes rogue, deciding to kill all human life on the Discovery One because he sees them as a threat to the completion of the mission. Brilliantly voiced by Douglas Rain, HAL has no anger, only cold business decisions to make and his desire to see the mission finished is second to none as Gary Lockwood's Frank Poole found out. The monotonous tone of HAL, even when he expresses fear is what makes him so creepy - his lack of humanity makes his decisions that bit more colder and cruel. Kubrick's film is extraordinary for many reasons and HAL is one of them - he's a villain that is impossible to figure out or understand because he is a computer who may or may not have human emotion and the ambiguity is what makes him so frightening.
17. Alex Forrest - Fatal Attraction
Played By: Glenn Close The original crazy stalker won't stop at anything to get Michael Douglas' attorney back into bed with her. After their brief affair, he goes back to his family but she wants him all to herself so does everything from suicide attempts to killing the family bunny to get his attention. Glenn Close plays Alex to manic perfection as she grows more and more mental as the films builds towards its chaotic and bloody climax. Alex still frightens men to this day, her unstable antics being a moral warning against infidelity as love literally drives her insane. She's unnerving, shrewd and unrelenting in her pursuit of Michael Douglas and for her sheer memorability she's one of cinema's greatest villains.