6) The X-Files – Ice
Between pricey special effects and shifting locations, The X-Files was always going to be an expensive proposition for Fox to maintain, despite the show’s global popularity, so the writers regularly devised ways to reduce costs using elements of the bottle episode format.
The most memorable example arrived early on in the first season, where FBI agents Mulder and Scully are called out to an Arctic research station to investigate the unusual death of a scientist. Events quickly escalate until it becomes apparent that the pair are facing an alien parasite that can infect anyone without detection.
Despite blatantly stealing its premise from John Carpenter’s The Thing, “Ice” is a masterclass in building tension and is often called upon as an early fan favourite. The episode is also pivotal for the way it brings Mulder and Scully’s conflicting ideologies to the fore, cementing the dynamic that fans worldwide would fall in love with for many seasons to come.