Probably the greatest living director of action movies. You could argue that James Cameron wears that crown thanks to Aliens and T2, but Miller's most recent movie was Fury Road while Cameron's was Avatar.
But wait, that's not all! He also wrote Babe and directed Babe 2, probably a top 10 and a top 25 ever kids movie.
He also directed a fully animated movie (Happy Feet — not great, but shows he can work with CGI).