These are not the best episodes, but the ones most important for catching up with the X-Files mythology.
With The X-Files coming back to TV in the not-too-distant future, I figure people are going to start watching the series to catch up. It's a long series with a complicated plot, and only some of the episodes are about that plot. So for those wanting to rewatch the show but not sift through the entire series, these are the essential episodes of The X-Files.
The first movie takes place between seasons five and six is and important. The second movie takes place after the series.
The complete extraterrestrial story lines and related conspiracies of THE X-FILES per Wikipedia, which combined information from series DVDs with information from the book entitled THE COMPLETE X-FILES: BEHIND THE SERIES, THE MYTHS AND THE MOVIES. Episodes included in only one of the two sources are still included here. Also included is the first feature film.
List of episodes I've watched in 2019.
New episodes: 241
Rewatched episodes: 0
Murder Mountain S1E01
Bob's Burgers S8
American Crime Story S2E03→S2E06
Chilling Adventures of Sabrina S1E11
Tidying Up with Marie Kondo S1
Star Trek: The Next Generation S6E23→S7
RuPaul's Drag Race S10E04→S10E14, S1
Sex Education S1
BoJack Horseman S5
Marvel's The Punisher S2
True Detective S3E01→S3E07
Star Trek: Discovery S2E01→S2E05
DC's Legends of Tomorrow S3E11→S4E08
Unbreakable Kimmy Schmidt S4
The Last Man on Earth S3E01→S3E03
The X-Files S8E06→S11
Selviytyjät Suomi S3E01
Planet Earth S1E01→S1E03
RuPaul's Drag Race All Stars S1
The Flash S3E01→S3E04
The Mytharc is the overarching story developed in a series of episodes of The X-Files where Mulder and Scully investigate and expose an international conspiracy by an organization known as the Syndicate to develop a human/alien hybrid and suppress knowledge of the existence of extraterrestrials who plan to colonize Earth.
It should be noted that some key mythology characters also appear in Monster of the Week episodes; notably, Deep Throat, X and the Cigarette Smoking Man each appear in episodes which involve government activities.
Furthermore, as his role expanded, Walter Skinner appears in more Monster of the Week episodes.