What is the name of the alien race that intends to colonize Earth in The X-Files?

The Colonists are the alien race that intends to colonize Earth in The X-Files. They are the central extraterrestrial antagonists of the series’ original mythology and work with the human Syndicate on a plan to take over the planet.

The Colonists are closely associated with the black oil virus, alien-human hybrid experiments, and the planned invasion date of December 22, 2012. Their mature form resembles the “grey alien” familiar from popular culture, but “The Greys” is not the formal name used by the series for this faction.

The Rebels are a separate alien group that opposes the Colonists and sometimes aids humanity. That opposition explains why viewers may confuse the two names, especially during the mythology-heavy episodes of seasons four through six. The term “Visitors” is not the canonical designation for the colonizing species.