The Dark Side of the Sun is a comic science fiction novel by Terry Pratchett, first published in 1976. It has very little connection with Strata and with the Discworld series, featuring much less comedy and parody than these. The Dark Side of the Sun makes many light-hearted references to famous science fiction works, such as those of Isaac Asimov. Terminology from the novel, including "Hogswatchnight" and "Small Gods," reappears with different significance in the Discworld novels.

The story is set in a portion of the galaxy populated by fifty-two different sentient species. All of these species, humanity among them, have evolved in the last five million years, and all of them have evolved in a spherical volume of space only a few dozen light-years across centred on Wolf 359. The rest of the galaxy is sterile as far as anybody can tell.