If you don't know about Häxan, then I recommend that you see it. It's one of the strangest of silent horror films, since it's really more of a documentary essay than a drama, although it contains dramatic illustrations of the European witch craze. There's also a didactic aspect to the film. Benjamin Christensen, the director, was familiar with the psychiatry and psychoanalysis of his day, and he attempts to demonstrate that the origin of the belief in witches and witchcraft has a psychological explanation rooted in the phenomenon of hysteria.
For my entry I made use of the DVD available through the Criterion Collection. As far as I know, that's the only version to be found in the U.S. Unfortunately, I don't know what other editions might be available outside of the U.S.