Häxan (movie, 1922)

Grave robbing, torture, possessed nuns, and a satanic Sabbath: Benjamin Christensen's legendary film uses a series of dramatic vignettes to explore the scientific hypothesis that the witches of the Middle Ages suffered the same hysteria as turn-of-the-century psychiatric patients. But the film itself is far from serious-- instead it's a witches' brew of the scary, gross, and darkly humorous.