Amarth

I can't believe you almost forgot Alucard your shmuck. Also, Legato is not a badass. He's a tool. Good call on Ein Starman Deluxe. Well, there are so many, so I'm going to try to pick ones not listed above. (Spike is there like 800 times, which he deserves to be, but I'ma go for diversity.)

Ban Mido - Getbackers - Evil eye? Most badass power ever!

Jackal - Getbackers - He has knives in his fucking body and he uses them to kill for fun. Now that's badass.

Vegeta - Dragon Ball Z - I know DBZ characters aren't typically badass, but Vegeta just is. He kills his own teammate for one thing, but more importantly, he's the only Z-Fighter who will kill the peons that are trying to kill him, even when they pose him no threat. Plus, he ate those mantis people which was just cool.

The Rock Dude - Ninja Scroll - He spilt more blood than anyone except maybe Alucard. Plus, he punched Jube through a frickin' rock.

(Was gonna put Vicious here, but he's already there.)

The Butler - Hellsing - Damn. Wires in the gloves. Slicey Dicey. Old man kickin some ass. That's badass.