Star Trek has always been open and eager to stretch their own crossover appeal. Thanks to clever time travel mechanics, mind-meld flashbacks, and other sci-fi plot contrivances, we have seen Tuvok talk to Sulu, Scotty talk to Picard, and Riker talk to Capt. Archer. This sort of playful crossover game is particularly appropriate for Star Trek, as–it could be argued–it was Star Trek that pretty much invented the notion of crossover canon (that is: The characters are having adventures beyond what we see on the show).

Thanks to the impassioned and unending blast of literary output that is constantly streaming from the fan-fic community, this notion of inter-textual crossover has long ago been expanded to a now-easily-accepted-and-perfectly-common extra-textual crossover. No enterprising Trek fan worth their weight in latinum hasn’t dabbled, for instance, with stories wherein Kirk or Picard has managed to meet–through however bizarre a set of circumstances is required–the characters from My Little Pony: Friendship is Magic. Or The X-Files. Or Bill & Ted’s Excellent Adventure. Or, I dunno, Turbo Teen.

That sort of enthused fan fiction had, over the years, become so popular that the people in charge of the Star Trek universe had begun to take notice, and (perhaps wisely, perhaps unwisely) began releasing officially sanctioned pop crossovers of their own. Most of these crossovers were bound in the pages of comic books, but at least one made its way into the literary world. Here are some of the most notable.

Star Trek and Doctor Who

Since Star Trek and Doctor Who debuted in the 1960s (DW: 1963, Trek: 1966), and that they are both about–more or less–spreading peace and benevolence throughout the universe using super-advanced spacecraft, they share an undeniable kinship in the sci-fi community. Fans of one tend to be at least respectful of fans of the other. There is no rivalry, à la Trek and Wars. It’s surprising, then, than it took until 2012 for the two franchises to finally meet in the comics, thanks to the good people at IDW.

In Assimilation², published by IDW, The Doctor (and Amy Pond) find themselves aiding the crew of the Enterprise-D to stop The Borg and the Cybermen from teaming up to destroy the galaxy. The Borg and the Cybermen bear a good number of similarities, so it makes sense they should be used together at some point. And while Doctor Who tends to be a TV series that is more adveturous in tone, the two franchises overlap pretty perfectly.

Star Trek and Planet of the Apes

Inspired by the success of the Doctor Who crossover, IDW, in 2014, published a series of crossover comics wherein Kirk and crew encounter Taylor (originally played by Charlton Heston) on a planet overrun by talking, intelligent apes. This is a good marriage because the Apes movies, although filled with a good number of dumb jokes and some admittedly silly imagery, were actually staged as morality plays. And morality plays are Star Trek‘s eternal stock in trade. So, yes, there is a gorilla wearing Kirk’s shirt in that picture, but it’s a serious comic.

A bit of triva: The likeness of Heston could only be used by a special agreement with his estate.

Star Trek and X-Men

In 1996, Scott Lobdell wrote this playful–but somewhat serious–crossover between the original Star Trek and the X-Men. In it, the X-Men fly through (all together now) an unpredictable spacial anomaly only to encounter Kirk at about the time of the events of the episode “Where No Man Has Gone Before.” Kirk and the X-Men team up to fight not only Shi’ar bad guys, but also the godlike Lt. Cmdr. Mitchell (originally played by Gary Lockwood). This issue was popular enough to warrant a sequel wherein the same spacial rift sends the X-Men forward in time to meet Picard. Says Wolverine to the crew of the Enterprise-D: “You Kirk’s people?” It’s a little mind-boggling.

Furthermore, that comic eventually gave way to a 1998 novel, written by Michael Jan Friendman, called Planet X, a bonkers affair that depicts a Star Trek planet that is undergoing a mutant crisis similar to what the X-Men have experienced. I have read it. Despite its attempts to make everything seem natural, the book is pretty dumb.

Since these crossovers all came before the production of the first X-Men feature film, all the characters could do was note on how Capt. Picard looked an awful lot like Prof. Charles Xavier. That Patrick Stewart would go on to play both roles was, in 1998, only a fan’s pipedream. Luckily, it came true.

Star Trek and Green Lantern

The Spectrum War is a 2017 comic book series in which the space-faring police force from Green Lantern encounters Kirk and Co.

I haven’t read it, so I can’t comment on it. I can say that the Green Lantern is such a weird idea unto himself (have you ever stopped to think about how bonkers Green Lantern really is? It’s off the wall), that it would take the relatively staid universe of Star Trek to perhaps ground him. Let him encounter less silly sci-fi ideas. Like Tuvix.

Star Trek and Aliens

As was reported in the pages of Nerdist not too long ago, it was announced that 2017 would see the release of another IDW Star Trek: The Next Generation crossover involving the creatures from James Camerson’s 1986 film Aliens. It will be handled by the same crew of writers and artists as the previous most recent IDW crossovers, although this seems like more of a challenge. Aliens is, after all, a wham-bang action picture about masculinity and bullets. Star Trek has always been more about diplomacy and solving problems with wit and intelligence. We’ll have to see what the creators come up with.

Significant: If the xenomorphs are now encountering Star Trek characters, that means Capt. Picard now exists in a plausible universe with all the other people the xenomorphs have encountered. Including the creatures from Predator, The Terminator, and Judge Dredd. And Batman has fought a Predator. And Batman has also teamed up with Ninja Turtles, and many Marvel characters.

I think we are this close to seeing a feature film version of The Ultimate Showdown of Ultimate Destiny.

Who or what would you like to see Star Trek cross paths with? Let us know in comments.

Images: IDW, Paramount, BBC, DC Comics, 20th Century Fox