One of the best events of a Star Trek series is the fan-serving crossover episodes, where characters from one series appear in another. These have occurred in all the modern series and whole-heartedly deserve their status as prestigious TV events, given how they unify fanbases, and their inevitable effect on ratings. And while some appearances were brief (such as Commander Riker in the Voyager episode Death Wish), others had the entire episode built around them - like Sarek - and the results have often been a mixed bag, despite how well the idea of cross-overs is invariably received. Inevitably, not all of the crossovers were such a good idea - like THAT Enterprise episode. And in other cases we've had very brief nods to the fans with thirty second appearances in episodes such as Quark turning up in Star Trek: The Next Generation - although he was also meant to appear in Star Trek: Insurrection but the scene was cut. Other episodes were just unsatisfying, like Sons of Mogh in Deep Space Nine. The best episodes are certainly an easier prospect to run through, and we will offer that rundown after this article, but to commemorate the fact that not every episode can be as great as perhaps was intended, we've compiled a list of the worst crossover episodes in Star Trek history. But of course, by virtue of the quality of the top 10 there are some good episodes in here - and remember to keep a key eye out in the future for when our run-down of the ten best Star Trek cross-over episodes is posted.
11. Emissary (Star Trek: Deep Space Nine)
Emissary was the pilot of Star Trek: Deep Space Nine; it turned the crossover cameo in a Star Trek pilot into an expectation. A lot of set up occurs in this episode but some of the more interesting scenes are those with Commander Sisko and Captain Picard. You see, at the start there is quite a bit of animosity between Sisko and Picard, as while Picard was assimilated by the Borg during The Best Of Both Worlds, the Borg destroyed the USS Saratoga resulting in the death of Sisko's wife. The Picard appearances bookend Emissary in order to show the character growth of Sisko during the events that occur in the episode. It was initially planned for there to be a major crossover episode with Deep Space Nine and the Enterprise-D for the end of the first series of DS9. This didn't happen (unfortunately for us crossover fans), and instead the first series was closed with In The Hands Of The Prophets instead. Emissary is the best Star Trek pilot when considered in hindsight, but because some crossover episodes are of such high quality that it pushes this one down to the worst list. A shame really, because I'm sure this would appear in many people's top 20 lists for DS9.