Santa Claus Conquers the Martians

The story of the depressed children of Mars. To bring them out of their funk, the Martian leaders travel to Earth and kidnap two local kids and Santa himself, forcibly installing them in a factory to make toys. But you can't manufacture happiness, and Santa must teach his alien overseers the true meaning of Christmas.

The Martians kidnap Santa Claus because there is nobody on Mars to give their children presents.