Your favorite badass game vilain/hero?

Vhailor from planescape: torment
Giant moving suit of armor that can kill immortals.

Ganondorf/Sam Fisher

Goffard Gafgarion from FFtactics. Very interesting antagonist.

Lavos!!!

Giygas. Simply because you cannot grasp the true form of Giygas's attack.

Geralt from The Witcher deserves a mention.

Of course it's the Prinny, dood!

the dragon that kidnapped mario's lover.

Villian : Jack of the Blades from Fable

Ah Jack. I hated his voice in Lost Chapters though.

Villain - Jon Irenicus to be sure. Letho was fairly impressive as well.
Hero - Probably Geralt. Maybe Minsc and Boo.

Sarah Kerrigan

Good: Thane Krios

Bad: Lu Bu

Took a lot of effort just to come up with two, guess I just really prefer the enigmatic character types :x (like Auron is a good example of what I mean)

E: hell even the two I listed are rather enigmatic.

Id, or "that red bastard" from Xenogears. "Dropping a sandcrawler on me is cheating. TAKE IT BACK."

I like a lot of the ones already mentioned, so I'll add another pair of protagonists (don't know if I'd call them heroes):
Subject Delta (BioShock 2)
Stranger (Oddworld: Stranger's Wrath)

Puffy Dragon from I love Kitty Adventures 2

Commander Shepard man....he saved the citadel from the geth attack and Sovereign and destroyed the entire civilization of Collectors plus he is going to kick Reaper ass in Mass Effect 3