I saw Alberto Sordi at an appearance he made in an art movie theater last year. Needless to say, the appearance was a sold out affair, but outside the theater, no one I spoke to had ever heard of the man. He made many films, and many among them stinkers, of which one followed the appearance I attended. Go figure! Still, you are right, he is, if not the greatest, one of the greatest.
At the same theater, not long after or before that (I can't quite recall,) Toto's daughter introduced one of his films.
Another fine Italian comic that comes to mind is the late Vittorio Gassman.