Super-soldiers (The X-Files)

Super-soldiers is the the main antagonists Season 9 are human replacements that look human but are actually a type of alien. Fearless and virtually unstoppable, these aliens are not directed by anyone and are answerable to no-one except their own biological imperative to survive. They want to knock out any and all attempts by humans to survive the alien colonization of Earth and were created to aid in the extraterrestrial repopulation of the planet. Their collective name, "super-soldiers," derives from the aliens themselves, but was often used cynically by humans.

Origins
After the destruction of the Syndicate by the rebels, the colonists began again to kidnap people who already had them. The colonists began to experiment on them to become super-soldiers to replace the dead members of the Syndicate to prepare for the colonization of the Earth. They began to destroy everything that was connected by the work of the Syndicate and began to hunt Dana Scully and her child.