In the series' plot, the Colonists are collaborating with a group of United States government officials known as the Syndicate in a plan to colonize the Earth, hence their name.

[4] Purportedly, the Colonists planned on returning to Earth in the year 2012, as The Smoking Man (William B. Davis) later remarks to Fox Mulder (David Duchovny) that the ancient Mayans were so terrified that they stopped their calendar on the exact date of colonization: December 22, 2012.

Shortly after this event, a select few power brokers, mainly in the United States and the Soviet Union (though some also came from other nations), first learned of the Colonist plot to retake the planet.

The distinguishing characteristic of the Rebels is that they have had all of their facial orifices sealed shut in an effort to avoid absorption of and subsequent infection by the parasitic black oil; this led to a somewhat grotesque appearance.

In the latter seasons of The X-Files, the role of the Bounty Hunters on Earth has largely been taken over by the Super Soldiers, human replacements capable of withstanding incredible amounts of damage.

In the two-part episodes "Colony" and "End Game", Chris Carter and Frank Spotnitz along with some help from David Duchovny created what would become a recurring character named the Alien Bounty Hunter.

After casting him, they told Thompson's agent that he needed a hair cut, because he was originally envisioned as a U.S. Air Force pilot who'd been shot down.

The Syndicate in cooperation with the alien Colonists developed a delivery mechanism that would be used to introduce the virus into an unsuspecting public upon colonization.

While the Purity Control project ultimately fails, a rival Russian shadow group was successful in developing a weak vaccine that eventually fell into the hands of the Syndicate.

The plot to cooperate with the alien colonization plan was implemented with the aim of being given access to the black oil for the transgenic corn, in order to perform experiments with it in an effort to develop a vaccine.

After the events of the 1998 film, the Syndicate, as well as Mulder and Scully, learned that the black oil can either take over a host's body or incubate within other life forms, including humans.

The Rebels are distinguished by their grotesque appearance: the orifices on their face are morphed shut to avoid absorption of the parasitic black oil.

Colonization has apparently begun in the Rebels' home environment, but members of this species are spared gestation to become Bounty Hunters for the Colonists' ongoing conquest efforts.

While the Rebels had an opportunity to destroy the hybrid, Cassandra Spender, they choose to let her survive in the hope that the Syndicate will join them in fighting the Colonists.

[19] At this point, a fully working vaccine has not been created, and it is therefore decided that the best thing for the Syndicate to do is to comply with the original deal and turn over the hybrid to the Colonists in the hope that they are spared the resulting takeover.

He said in the commentary of "One Son" that the faceless rebels and the human race are the only two species of advanced civilization in the galaxy that have not been consumed by the black oil.

These clones have the same caustic greenish blood of the aliens, have greater muscular strength and higher physical endurance levels than most normal humans, and can breathe underwater.

Cassandra is a hybrid created through a process other than cloning, and worked on by both the Syndicate and the aliens themselves, although the exact methods used to transform her are never fully revealed.

[19] For years, Cassandra was under the mistaken impression that she was to be an emissary of the aliens to spread a higher spiritual understanding to humanity,[4] but after her final abduction in the late 1990s she comes to realize the truth.

He believed that Mulder had, in effect, become a perfect alien-human hybrid and that by taking his genetic material, he would be able to continue "The Project" and survive the coming alien onslaught.

[26][27] To create Super Soldiers, the Colonists infect humans with a new strain of their virus, which slowly destroys and then rebuilds the body of the host.

[28] As they have normal red blood and can replace individuals within powerful positions, they provide an ideal way for the Colonists to infiltrate humanity to ensure that the plans for colonization are uninterrupted.

They are identifiable however by small spiny protrusions on the backs of their necks or by detailed analysis of a blood sample which shows their DNA exists as a complex with iron.

[30] The only known way to kill them takes advantage of their metallic biochemistry: their bodies are torn apart by the magnetic fields present near large deposits of magnetite ore.[31] The Super Soldiers quietly fill the positions of power previously occupied by Syndicate members and rarely use human conspirators.

By the end of season 9 they virtually replaced the Syndicate and were successful in chasing Mulder and Scully out of the FBI so that they can no longer investigate the X-Files and interfere with their plans.

Club was highly critical of the final season and its mythology story, noting that the "new serialized storylines about so-called 'super soldiers'" resulted in a "clumsy mish-mash of" ideas that worked and did not.

The site wrote moderately positively of the Super soldiers and applauded the show's continuity, citing their decision to make Billy Miles the first super-soldier.