Maltmonster posed an interesting List: not content to discuss the five best trilogies, he posited a selection of the best three movies made by a single director.
With that in mind: please list five directors who each have three movies that are superlative beyond the norm. Just to make life interesting, Steven Spielberg, George Lucas, Sidney Lumet or Billy Wilder are not to be a part of your final list. You are also to exclude any self-contained trilogy (or any of its individual constituent films) like LOTR, Bourne, Jurassic Park, Mad Max and so on.
Gentlemen, have at it.