God I love it when they let superman be all wholesome. This is one of my favorite episodes of Justice League in no small part because of Clark just acting like a big kid on Christmas. It's right up there with that time Supermen gave a little PSA speech to a kid, whose only response was "What a dork!'
If they would make a Superman movie like this instead of trying to make him darker and broody, I would be so happy.
Comfort and Joy. Clark brings J'onn J'onzz home with him for Christmas, and there are side stories with Flash and also Green Lantern and Hawkgirl. You can watch this episode as a standalone Christmas special if you like, no special context required.
Arguably the best episode of the best Justice League ever put on screen, including comparisons across TV, video games, and movies.