The two oldest science fiction franchises that routinely put out new content are the BBC’s Doctor Who and Paramount’s Star Trek. Doctor Who started in 1963, three years before Star Trek, which premiered in 1966, but was a concept in the works as early as 1964. The two science fiction franchises have been staples in the fandom for decades, and while they’re different in some aspects, they both embrace the whimsical aspects of science fiction.
Yet, while they embrace some aspects of one another, they are, at their core, radically different. Doctor Who can be heavy, but it’s very whimsical in a sense and focuses more on the interpersonal aspects between the characters. And while Star Trek also has interpersonal aspects and conflicts, Star Trek uses its characters to bolster and fortify its plot. See one could argue that the characters carry the core of Doctor Who, while Star Trek’s plot carries the characters.
It’s a small but obvious difference. It’s a key reason why the two shows have radically different tones. The Doctor is a do-gooder who wants to impose his will on situations that are deemed wrong. Star Trek (when done right) is about one more moral issue after another and how a group of characters deal with it. That core focus of each show is why the two shows would never work as a crossover. Even if The Doctor Who franchise is now alluding to wanting a crossover; as seen in the series’ most recent trailer. The new Doctor is seen in the trailer for the upcoming season (or series if you’re in the UK) referring to the fact that in the Doctor Who universe, Star Trek exists and that they should visit it.
A notion that many may have liked in 2006 but with how polarizing both franchises have become due to a comedy of errors across the shows, a crossover is now a haunting idea. The franchises are too different to work in the same show and while some fans would love the novelty of the experience, many others would be put off. Either Star Trek would have to be a bit more whimsical for Doctor Who, or Doctor Who would have to be a lot less cheery. While some would argue both shows have gone in the other’s direction, it’s worth pointing out that the core of the shows are not the same and we’ve seen before, that when Star Trek more than anything, goes off course from what fans expect, it isn’t well received.
There may be fans who want to see the two shows converge, but that would be a bad thing to happen for both franchises. Especially when you realize how much work both shows need to put in to regain the goodwill of their fandom.