I've always considered Meet Me in St. Louis and Shop Around the Corner as Christmas movies, lol. Little Women, too, although I see the distinction. Remember the Night might fall into the same category or even Holiday Inn.
Superman: The Movie has absolutely nothing to do with Christmas, but I associate it with Christmas because it opened in December of 1978 when I was around 10. It was one of my favorite Christmases, kind of my last childhood Christmas. my older brother is 11 years older than me and was in dental school at the time. He took me Christmas shopping for our parents and then to see the movie and a milkshake afterwards. It's among my favorite childhood memories.