Jonah, sorry for the late reax, but I do believe Shaw takes the cake. His underlying problem was monstrous pride, compounded by a strange streak of inhumanity. Not, as that term is usually understood, cruelty–but detachment from normal human emotions. The wonder is that, with these defects, he wrote so well, and plays no less, where one must create many characters. The plays have their limitations too: Yeats compared attending one of them to listening to a great clattering sewing machine.
BTW, I did once read a quotation from Ezra Pound, praising Lenin’s piercing intelligence. That plus Mussolini is a bad day’s work, but Pound was much more a black shirt. His vileness lacks the versatility and depth of Shaw’s.