Great idea for a thread!
Here's my list-me-do:
1) Darth Vader
The ultimate genre villain turned anti-hero, courtesy of the prequels, Vader scared the holy smokes out of audiences young and old, and for that he deserves the top spot. Doesn't hurt James Earl Jones' voice lends the character a suitably sinister timbre.
2) The Joker
Why so serious? The Joker is a classic, timeless villain, in print and on screen. He is also an inspired choice for Batman's nemesis - what is the polar opposite of a crimefighter who dresses as a bat? A complete lunatic who thinks he's a clown, of course!
3) The Terminator
Holy moley. Easily Arnie's best role, the Terminator was an electrifying and terrifying screen presence. The most disturbing thing wasn't that he would not stop, ever, until his target was dead - it was that so many audience members actually liked
the carnage he wreaked. For getting his chrome claws so deep into his audience's psyche, this antagonist will never be forgotten.
Through the magic of CGI and Robert Patrick, James Cameron and co managed to top the sheer menace of the original Terminator. The T-1000, the Porsche to the Terminator's Panzer Tank, was a hit with audiences because he was so physically different from the previous villain, yet so thrillingly relentless. And the liquid metal eye candy (well, it was pretty sweet, state-of-the-art eye candy in the 90s) helped.
5) Agent Smith
Ah, Agent Smith. Pitch-perfect casting absolutely made
this character. Sure, suited Smith is a great inkblot villain for the audience to project their own hatred onto (is he simply a meddling Fed? Or a symbol of the injustice of The Man? Or is he just your garden variety butthead corporate boss?), but few can deny the effectiveness of Hugo Weaving's delivery of 'Mister Anderson!'
6) The Shredder
I don't know how high Kevin Eastman and Peter Laird were when they conceived of the Teenage Mutant Ninja Turtles, but it must have taken a legendary bad trip to come up with this nightmare-fuelled ninja-samurai-spiky-object-hybrid. Sure, the 80s cartoon made him into an incompetent moron voiced by Uncle Phil, but the original comics, as well as the original live action film, presented Shredder in all his razor-throated, Vader-with-a-blackbelt glory. And he has possibly the most awesome entrance ever made.
7) Benjamin Linus
Excellent casting, combined with excellent material, does indeed a great screen villain make. Especially when that same casting and material leads to performances so powerful, the audience actually sympathises with the villain at several points, so much so the character can arguably be viewed as an anti-hero rather than a villain. One of the best villains of recent times.
8) Colonel Quarritch
The thing with Avatar is, take away the stunning 3D cinematography and ignore the state-of-the-art CGI, and you're left with a relatively weak, if epic, science-fiction fantasy film that goes through the motions of the Lost-Earthman-meets-Last-of-the-Mohicans space opera subgenre rather than attempting to break new narrative ground. But you're also left with Stephen Lang as alternately sympathetic and genocidal mercenary leader Quarritch. He's great fun to watch no matter your depth perception.
9) M Bison
As a videogame villain, Bison is pretty one-note. Yeah, he looks cool, mostly because he discards his cape before every fight, but Street Fighter II didn't exactly allow its characters to emote while they were twisting their bodies into spinning torpedos of flaming death. But Raul Julia as Bison in the otherwise terrible Street Fighter movie is an absolute joy to watch, gleefully hamming it up so far he is the simply the best part of the entire film. And if you don't agree, you obviously haven't seen this bit.
Zachary Quinto loves his job. Even when the show he stars in is in dire straits, he effortlessly and tirelessly entertains his audience, combining menace, violence and humour into a charismatic villain everyone loves to watch.
11) Anton Ego
Well, this thread is
about antagonists rather than villains, and Ego is at the very least antagonistic. Mixing morbid imagery (look at that face) with witty dialogue given life by brilliant voice acting, by Ratatouille's end, Anton Ego is the most sympathetically acerbic food critic who never lived.