28. The Terminator
Appears in: The Terminator (1984)
Scariest moment: In the form of Arnold Schwarzenegger, the robot assassin in The Terminator (1980) warns a police officer "I'll be back," a quote that's been rendered corny today but was rather chilling at the time of the movie's release.
Weaknesses: Hydraulic presses and anything else that can crush metal.
The word "monster" implies many things: enormous animals, undead stalkers, pint-sized demons. Monsters come in all kinds of forms, and in the world introduced in James Cameron's seminal The Terminator, they're actually robots, though their metallic forms don't stop them from being some of the deadliest monsters in all of cinema.
Built by Skynet, an advanced artificial intelligence from the future, the killing machines, or "endoskeletons," were designed to resemble humans, from the ways in which they move to their physical makeups, usually covered in synthetic skin. The key difference being, of course, that flesh-and-blood folks can't withstand dozens of bullets, nor can they intimidate foes by simply flashing their red, laser-beam eyes.