Count of Monte Sawed-Off
un33dab@dpu$$y
I wouldn't put him in Ashley's tier, but he's certainly not guilt-free like the others, everyone else is capable of fucked up shit, but shooting someone certainly isn't one of those things, so I'd say he's a distant second in the evil scale, the other characters have flaws, but none of them has any "evil" in them other than those two.
I think you'd also have to throw Chris in there too then. He can choose to shoot Ashley when given the choice.