The problem with science fiction is that each series tends to paint the history, technology, geography, and physics of the universe in a different way, so it's rare to find two SF franchises that can cross over. The only non-Trek works that I consider to be part of the Trek universe are other Roddenberry pilots -- The Questor Tapes
(which a few Trek novels have very subtly hinted might be part of the universe) and Genesis II/Planet Earth
(which I consider to be the alternate timeline that would've resulted if Gary Seven hadn't intervened in Earth history, as discussed here
Pretty much anything that shows Earth making contact with aliens before 2063 is out, so no Alien Nation
. No The 4400
, since there are very few superpowered humans in the Trek universe (basically just the occasional esper) and since time travel (a big deal in The 4400
) is initially seen as only a theoretical possibility in Trek's era.
So yeah, we'd probably be dealing with SF-lite shows like The Man from UNCLE
. In the course of watching it on DVD, I've wondered if it could be considered part of the Trekverse, but I think it's a little too goofy, and it gets rather campy later on. The Avengers
(the '60s spy show, of course) also got rather comical and fanciful at times.
The Six Million Dollar Man
and The Bionic Woman
are interesting candidates, since they show a rather more advanced space program in the '70s than we had in real life, which is consistent with TOS's portrayal of human spaceflight. But then, what happens to that nifty bionics technology? Is it lost in the Eugenics Wars or WWIII? And in that case, can you count the '90s reunion movies?