3. Led Zeppelin Houses of the Holy
Like Presence, the cover of Led Zeppelin's Houses of the Holy had its basis in science fiction. This time it was a novel by Arthur C Clark called Childhood's End that provided the inspiration for Thorgerson's otherworldly photograph. In the novel "kids from the future were imagined to coalesce spiritually in mass mutation and leave the Earth as a tower of flaming energy" in an interview with Classic Rock. It is a piece of pure imagination with weirdly inhuman children (naked of course, because it was the 70s, so this wasn't frowned upon in quite the same way it would be now) climbing up towards a bright orange light, which could represent almost anything. The apocalyptic landscape may not look like any real place on earth, the photograph was actually taken at the Giant's Causeway in Northern Ireland, at sunset to achieve that distinctive lighting effect.
2. Muse Black Holes and Revelations.
Thorgerson returned to his prog-rock roots when he worked with Muse, beginning with 2003's Absolution, but it was his cover for Black Holes and Revelations that would prove one of the most memorable of his later career. That fact that Muse's lyrical content drew heavily on both real science and science fiction (far more so that Zeppelin of Floyd) made Thorgerson the perfect cover designer. With its otherworldly landscape populated by strange figures doing odd things the cover for Black Holes and Revelations could just as easily have been taken from some pulp sci-fi novel from the 50s. It's hard to think of anything more appropriate for an album that included song titles like "Starlight" and "Supermassive Black Hole".