The X-Files 3

The X-Files 3 was a planned science fiction film which would have served as the third film in The X-Files film series, which is based on the popular television series of the same name which originally ran from 1993 to 2002. It was also expected to act as the conclusion to the series and finish off the myth arc involving an alien invasion, which had been referenced to several times in the main show and the first film. It likely would have been written by the show's creator Chris Carter, although it's unknown if he would have directed it like the last movie.

Plot
The film likely would have dealt with the alien colonization of earth that had been foreshadowed several times throughout the main series run and was given the set date of 2012 in the original series finale "The Truth" (which aired in 2002).

Cast

 * David Duchovny as Fox Mulder
 * Gillian Anderson as Dana Scully
 * Mitch Pileggi as Walter Skinner

Why It Was Cancelled

 * 1) The poor performance of the 2008 sequel The X-Files: I Want to Believe (which was standalone and had nothing to do with aliens) likely had something to do with a third installment not being made.
 * 2) The intention was to release the film for 2012, as it was the same year the alien invasion was meant to take place. As time went on and got closer to the date, it meant there was no time to make the film and get it out on time to tie with that year.
 * 3) After 2012 passed it was announced the show would instead continue with a miniseries in 2016, which would serve as a continuation of the original 1993-2002 series.

Results

 * A third film was cancelled and the The X-Files returned for an "Event Series" run of 6 episodes in 2016. The original deadline of the 2012 alien invasion was ignored and instead the show moved forward with a new mythology.
 * The revival series finished after its second run in 2018 due to low ratings, bringing an end to The X-Files franchise for the time being.