It's an unwritten rule of television that when you get at least a half-season order for a new series, you have to make room for a Christmas episode. Of course, some shows break this rule, but they do so at their peril. There's no surer way to get new viewers to fall in love with recently introduced characters than to show them struggling with the highs and lows of the yuletide season. How tried and true is this approach? "The Simpsons" began with a Christmas episode in 1989 ("The Simpsons Open Fire"), and is currently in its 36th season.

While some shows are quick to discover that Christmas episodes are a tradition, their viewership expects to celebrate at least every other year (The Big Bang Theory celebrated the holiday six times over its 12-year run), others mined the sentimental season more sparingly. Basically, the longer a show or franchise runs, the more likely the writers and producers will go back to the Christmas well for seconds and thirds. So when you're dealing with a 58-year-old brand like Star Trek, you'd understand that there are multiple Christmas episodes scattered throughout its many different series. But just how many times has the franchise created by Gene Roddenberry gone bonkers?

There is not a single Christmas episode in the Star Trek television canon. Was Roddenberry a big Grinch who banned his mention from any series bearing the brand name? Not really. It's just that Christmas and Christianity in general are irrelevant in a future built around secular humanity (and there is a brief Christmas scene in the 1994 film Star Trek Generations). This doesn't mean you have to take a break from Star Trek for the holidays. According to StarTrek.comthere are 10 episodes from various incarnations of the franchise that express Yuletide themes or at least have a Christmas atmosphere. They are as follows:

• "The Trouble with Tribbles" — "Star Trek: The Original Series"
• "New Ground" — "Star Trek: The Next Generation"
• "You're Cordially Invited" — "Star Trek: Nine Space Into Deep Space"
• "11:59" — "Star Trek: Voyager"
• "Silent Enemy" — "Star Trek: Enterprise"
• "Forget Me Not" — "Star Trek: Discovery"
• Nepenthe — Star Trek: Picard
• "Taken" - "Star Trek: The Lower Decks"
• Kobayashi — Star Trek: The Prodigy
• "Spock Amok" — "Star Trek: Brave New Worlds"

As a casual Star Trek fan who has had trouble keeping up with the onslaught of new series (which I'm sure I'll love when I get around to them), I can absolutely vouch for the pointlessness of "Trouble With Trouble" and the Worf-centric "New Ground" and "You're Cordially Invited." It turns out that everyone's favorite Klingon is the perfect vessel through which to reinforce the Christmas themes of family, friendship and forgiveness.

Of the others, you can't beat Nepenthe for a good cry. This is the Star Trek: Picard episode that brought back Patrick Stewart's eponymous character alongside Riker (Jonathan Frakes) and Troi (Marina Sirtis), and it delivers warmth and melancholy in equal measure. I will list the others on my must-see list and encourage you to do the same. You don't have to explicitly celebrate Christmas to embrace what makes the season so valuable around the world.