Funny thing, there's actually one Lantern that is about Greed (Orange). At least according to TV Tropes.
Yup. His name is Larfleeze. Uses his ring to devour the souls of anyone who seeks to steal the power from him, then turns them into constructs serving his will.
I dislike that comic, if only because I think it strays dangerously close to being anti-capitalist. Corporations aren't inherently evil, nor is profit. Nor is greed, in small doses, all bad.