So here are the main ingredients I see as necessities for every Christmas movie.
1) A title with an obvious festive link. Throw in the word Santa or Christmas, of course, and you're all set. But you can also use anything with the number twelve (The 12 Dogs Of Christmas, The 12 Disasters Of Christmas, 12 Dates Of Christmas, Twelve Trees Of Christmas, etc, etc) or just stick the word holiday in there (Holiday Inn, obviously, Holiday Affair, Holiday In Handcuffs). And using, or misappropriating, a famous Christmas Carol title or phrase can always work (a la every movie in the Silent Night, Deadly Night series).
2) Snow. You CAN have a Christmas movie without snow but I can't think of any examples just now. Snow doesn't automatically equal a Christmas movie, however, but the two go together like milk and cookies. There's even a Christmas movie simply called Snow (which also has a sequel).
3) An abundance of decorations, HUGE trees, and everything else that we don't always tend to have here in the UK. Much like the Halloween decorations, America really pulls out all the stops for Christmas. There are people who also do the same over here but they're a bit fewer and farther between. If you can reach the top of your tree without a stepladder in America then you may need to go shopping for a bigger tree. And it's that kind of spectacle that makes me watch average Christmas movie after average Christmas movie.
4) The main character names. Here are the most popular choices, based purely on my recollection of the many movies I have watched and with no grounding in actual facts or scientific study (apologies, but it's the way of the internet so I should be okay): Carol, Nick, Chris, Kate. The first three are obviously connected to the season. The fourth is just a popular common name to use in TV movies, as far as I know.
5) The cast can make the difference between your movie being simply distracting or moderately enjoyable. You could always choose to rope in some celebrity who is a bit past their prime, either for a main or supporting role. Or you could hire Christina Milian,who has popped up in a few Christmas TV movies, or Lindy Booth.
6) Romance. Many of the movies I've already mentioned have a love story at the heart of them. Even Santa himself has been looking for love in a few movies (such as Single Santa Seeks Mrs. Claus). It would seem that Christmas is the best time of year to find love, possibly because it can be viewed as a gift and a shot at redemption for some.
7) A non-believer. Whether it's someone doubting the existence of Santa Claus or even completely refusing to give in to the many delights of the season, every festive film should have a Scrooge.
8) Santa. Why did it take me this long to list Santa? Well, just as many Christmas movies don't feature the jolly fat fellow. But even when he's not in the middle of the action he's often watching over the main characters, perhaps helping to tweak destinies and cause happiness whenever possible. When he's not running the operation at The North Pole, figuring out how to keep his magic working and trying to make sure Christmas isn't ruined for everyone (e.g. Santa Claus, The Santa Clause, and many more).
9) Elves. You could easily argue that elves have saved Christmas a lot more times than Santa. They make the toys, they often make the best hot chocolates, and someone has to clean up all that reindeer dung. Yes, elves appear in many Christmas movies. And if they're not onscreen then you can usually find a character who has certain elfin qualities.
10) Kids. I know, I know, I should have mentioned them earlier. Christmas is for the young, and the young at heart, so it's no surprise to find so many of the movies featuring children. If there's not a main role for a doe-eyed minor then you can usually find them in a supporting role that will either perk up the lead or remind everyone of the true meaning of Christmas. Having a "Tiny" Tim often helps to add some extra magic to the grand finale.
11) Ending on a miracle is acceptable in any Christmas movie. In fact, it's almost obligatory. The miracle can be big (someone finding the power to get up out of a wheelchair and walk, for example) or small (friends coming around to help someone with that competition entry that could lead to a much-needed grand prize win).
12) If you can get a popular tune in there then that is the bow wrapped around the main present. A bit of "Let It Snow" is always welcome, but the musical score just has to reference "The Dance Of The Sugar Plum Fairy" and I am happy.
And there you have it. All the ingredients for a fine bit of Christmas fare. Here is a Letterboxd list I keep adding to, for all your Christmas movie needs. And for anyone still doubting it, of COURSE Die Hard is a Christmas movie.
Ho ho ho.