Gordon Freeman? Yeah, the guy's pretty badass, but he's got (what's left of) Black Mesa supporting him. Not to mention his HEV suit, which is all that's really keeping him alive - what, with all the car crashes he's been in. I mean, Gordon Freeman's either a really bad driver or he just needs another new car.
Put me down for Father Grigori. He's gaming's biggest badass. It's just him and his shotgun Annabelle in Ravenholm. Gordon spent a couple hours in Ravenholm, Father Grigori lives there and sets crazy traps in his spare time. He's Ravenholm's lone survivor. He's a badass.