What about Sid Vicious? He did blind someone with a glass and he allegedly killed his girlfriend. Mind you, I think that was largely accidental.
Phil Spector (allegedly). I think actually killing people probably lends you a certain hardness. Even when he wasn't shooting actresses (allegedly), he used to terrify people waving his gun around in the studio.
And what about Sly Stone in his prime? The monkey-fucking dog he had... the drug dealer who went missing.... I should probably stop now.