Sci-fi spin-offs can be a mixed bag. "Star Trek: The Next Generation" and "Stargate SG-1" were so successful that they spawned numerous follow-ups of their own, but efforts to expand the respective universes of "Babylon 5" ("Crusade") and "Battlestar Galactica" ("Caprica") proved rather less successful. Both were cancelled after a single run of episodes.
"The X-Files" spin-off "The Lone Gunmen" — whose final instalment debuted 25 years ago — belongs in that same one-season wonder category, but was rather better than its premature axing might suggest…
