Who is your favourite director, why, and what do you consider their magnum opus?

[Vinther1991]

I have a long list on directors I love, but if I have to narrow it down to a handfull then:

Brian de Palma - Femme Fatale
Michelangelo Antonioni - Zabriskie Point
Nicolas Roeg - Bad Timing
Federico Fellini - 8½
Stanley Kubrick - 2001: A Space Odyssey