2. T-1000 - Terminator 2: Judgement Day
Topping the villain of James Cameron's The Terminator was going to be no easy feat; Arnold Schrwarzenegger created such a physically imposing, terrifying, seemingly unstoppable monster that it didn't seem possible to make something any more horrific. With the unlikely, slender frame of Robert Patrick, however, Cameron created the T-1000, a distinctly more advanced cybernetic organism comprised of liquid metal, making it capable of imitating anything it comes in contact with, and also forming simple objects like stabbing weapons.
Best Moment: Too many to name, though the most iconic is surely the climax of the viaducts chase, whereby the T-1000's truck explodes, and as the T-800 and John Connor speed away, the T-1000 reveals its liquid metal form as it steps out of the fire. A landmark moment in visual effects that still holds up incredibly well today. What's more, the series has never found a villain even remotely possible of competing with it (to date, anyway).