Black Sabbath is a 1963 Mario Bava anthology horror film starring Boris Karloff. There were 2 releases of this film, and the American version differs markedly from the Italian, completely changing the plot of one of the 3 episodes (the middle one in the version below) to make it more suitable for American teen audiences. Boris Karloff plays host, introducing each segment, and he appears in the 3rd story. I'm not a fan of anthology films, and this one does nothing to convert me, but the 3rd is my favorite of the 3.
Hulu has the American version online with some commercials:
Moria says it's second only to Black Sunday of Bava's gothic horror films. 1000 Misspent Hours says it "remains a solid example of both its peculiar subgenre and work of its director." Images Journal has a review.