Back in the ‘70s, heavy metal wasn’t just a genre of music. It was also a monthly graphic novel magazine for adults that lived in the worlds of fantasy and sci-fi. It was a natural to be made into a movie since its influence was already working its way into sci-fi flicks like Alien. And with the help of Ivan Reitman (who'd go on to direct Ghostbusters), a seven-story animated anthology version of Heavy Metal made its way into theaters on July 29, 1981.

The movie -- like American Pop, which was released earlier the same year -- was an R-rated animated film for adults. Both big-screen ventures were hoping to make cartoon movies that would appeal to older viewers. And like American Pop, Heavy Metal came with a rock-heavy soundtrack that featured a varied lineup of artists -- from Blue Oyster Cult and Black Sabbath (who contributed "Mob Rules" to one of the film's highlights, a bloody battle scene), to Stevie Nicks and Journey.

Plus, the soundtrack -- which was released around the same time as the movie -- boasted two songs with “heavy metal” in the title: a self-titled Sammy Hagar jam and Don Felder’s “Heavy Metal (Takin’ a Ride).”

The soundtrack, like the film, is an odd mixed bag, and both are interesting time capsules of early '80s pop culture. The magazine was owned by the same company that published National Lampoon, and a lot of Lampoon-style humor and irreverence creeps into the movie. But the soundtrack also captures how the landscape of music was starting to change at the beginning of the decade, with old-school hard rockers like Grand Funk Railroad sharing space with New Wave weirdos Devo.

The release of both DVD and CD were held up for 16 years because of the music rights. Heavy Metal saw a brief re-release to theaters in 1996 to test the waters for the home-video version. A lot of it is now dated, but it’s a fascinating document that tried to push the boundaries of what hand-drawn animation's possibilities.

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