Just for the sake of arguement, do we count healing factors? I've always had the impression that a healing factor helped mitigate pain and make it more tolerable. or at least give the mental comfort of knowing it will heal.
I'd put Orion in if we count those. He's been stabbed in every fatal area on his body, and he was still able to get away to Himon. Not to mention having his energy drained for over a month and still having enough juice left to overload Metropolis's power plants.
Not counting them, Joker. Gordon shot him in the leg during No-Man's land. Joker wasn't even phased. He just started laughing after he realized it was because of what he did to Batgirl. Or when Jason Todd beat him with a lead pipe. He shrugged that off too.
I could count Azrael, but I think I'm the only one who actually liked him. 🙁