Alien

An alien, or more accurately extraterrestrial, is any life-form originating from beyond the planet Earth.

Sentient races

• Greys, a race of aliens with mysterious ties to the planet Earth and its history. These aliens are sometimes also referred as Reticulians for their supposed planet of origin, Reticulum, although abductee Cassandra Spender implied the importance of the constellation Cassiopeia to their origin. The greys include the colonists, although not every grey appears dedicated to colonizing Earth. Note that long-clawed aliens appear to be just a different stage in the life cycle of a grey. In recent decades, some of the greys attempted to recolonize Earth after an ice age forced them to leave; it is stated that they arrived here "millions of years ago" and "walked the Earth before the dinosaurs" in one form or another. Greys in their early stages of life look like yellow and green muscular humanoids with reptile like skin, clawed hands, large black eyes, slits for a nose and a mouth full of sharp teeth. After exposure to immense heat, they transform into an adult grey, which is about the size of a human child, whereas the immature form of a grey is as big as an adult human. They retain most features of the immature version except they lack muscular bodies, green and yellow reptile-like skin, sharp teeth and claws on their hands. Instead, they have frail bodies that are smoother and grey in color with larger heads in proportion to the rest of their bodies.
• Faceless aliens and alien bounty hunters, shapeshifting aliens who may be greys themselves. Faceless aliens are free of the black oil (see below) and have mutilated themselves, sealing all openings in their faces, to prevent it from infecting them.
• Purity (also referred to as "black oil" or "black cancer") is an intelligent alien virus that is the "life force" of the colonists. The virus can enter a human body to control it, up to and including control of the host's fine motor functions and speech that can deceive even those closest to the host, and can also emit lethal levels of radiation from the host's body when the alien intelligence chooses to do so, which does not appear to harm the host. Under different circumstances, the virus can incapacitate the human host and incubate an immature grey (a long-clawed alien) inside its body.
• Kindred: The Kindred look and act like a group of separatist religious such as the Amish, but it is implied they are really gender-changing aliens. They apparently lived on Earth until Mulder and Scully learned too much about them, causing them to flee, leaving strange indentations in corn fields that resemble the outline of flying saucers.
• Martians: Martians are gas based lifeforms native to Mars. They can travel in space without ships and are able to possess other creatures such as humans. Besides their gaseous bodies, they have faces that look like twisted human faces, which they can even form when possessing a human. They are known to sabotage human space flights, and one possessed Marcus Aurelius Belt during a space mission when he was an astronaut. However, Marcus managed to throw himself out a window, killing himself and the Martian.
• Mammalian beings
• Super soldiers
• Hybrids
• Clones

Known sentient aliens that appear human

• Bounty hunter
• Jeremiah Smith
• Josh Exley

Other alien creatures

• Alien spider
• Feathery serpent
• Parasitic ice worm

Appearances

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