Fire of Unknown Origin is the eighth studio album by the American rock band Blue Öyster Cult, released on June 22, 1981.

Several of the songs were intended for the soundtrack of the animated film Heavy Metal, such as "Vengeance (The Pact)," the lyrics of which follow in detail the plot of the "Taarna" segment of the movie.

The title track was used in episode 17 of season 1 of Supernatural entitled "Hell House," written by long-time BÖC fan Trey Callaway.

The album's closing track, "Don't Turn Your Back," marks Allen Lanier's final songwriting contribution to Blue Öyster Cult; it was played live by the group for the first time on June 17, 2016, at a special concert highlighting Lanier's music.

A music video was created for the song, which was banned by MTV for featuring a sexually suggestive scene.