'Christmas on Ganymede' is a science fiction short story by American writer Isaac Asimov. It was written in December 1940, first published in the January 1942 issue of Startling Stories, and reprinted in the 1972 collection The Early Asimov and the anthology Christmas on Ganymede and Other Stories, edited by Martin H. Greenberg. It was the twenty-sixth story written by Asimov, and the nineteenth to be published.

'The writings of Isaac Asimov do not always display his quirky sense of humor. This story, however, which first appeared in a 1942 edition of Startling Stories, certainly does.

The tale takes place on one of Jupiter's moons, Ganymede, where a home sick Olaf Johnson shares the legend of Santa Claus with the ''Ossies'' (local inhabitants) who are employed by the same company he works for. The Ossies' embrace the story whole-heartedly and declare a shut-down in production unless ''Sante'' pays them a visit. Will Olaf be able to re-create this Earth legend in outer space? Will Olaf keep his job after Commander Pelham (his boss) learns what he has done? Listen and find out!