Alien

Aliens are an extraterrestrial green yellowish humanoid race from an unknown planet. The only thing known about them is that they use their ability of space travel to study other planets and species.

Background
It is not known from what system and what planet they come from. Orbiting and observing the Earth with two motherships (Zeta and a unnamed one) at least since the 1600s in the Solar System, humans had no real awareness and no evidence of their existence. Before the 1960s, they were only believed by "crackpot" groups such as Quaere Verum, the only thinking that aliens exist and thought to be covered up by a government conspiracy.

But after the mysterious disappearance (abducted by aliens in Zeta in fact) of the USSA space capsule Clarabella 7 and the pilot astronaut Colonel Hartigan during the 1960s Space Race, the aliens became nationally recognized. It is said that alien technology was the basis of many of the Enclave's more exotic and impressive weaponry and robotics. Toy manufacturers such as Wilson Automatoys weren't immune to these accusations and the pre-War United States government, which was said to keep its alien specimens and technology mostly in Area 51 (like a flying saucer that was after re-captured by aliens but crashed in California probably during the flight sometime after the Great War, instantly killing the two aliens pilots).

The Brotherhood of Steel around 2161 and the Shi around 2241 have encountered the bodies of aliens or their spaceships. By extension, the Capital Wasteland Brotherhood of Steel have 72x alien power cells in the Citadel's armory and the Brotherhood Outcasts also have some alien power cells at Fort Independence. Also before 2277, an alien body was discovered in Fort Bannister, probably by the Enclave, carrying what may have been recovered (like an alien blaster and some alien power cells) in the armory of the Mobile Base Crawler at Adams Air Force Base.

Some of the advanced human technologies were created by using the alien technology like the AI project number 59234, created in the 2050s who manages the entire Sierra Army Depot Skynet, the device blocking telepathic and psychic commands, the psychic nullifier and probably the advanced accelerate organic tissue's regeneration processes gel mostly used for brain bots (robobrain, humanoid brain bot, think tank) the bio med gel developed at the Boulder Dome.

Biology
 Aliens are small, sexless green yellowish-skinned diminutive humanoid beings that possess a green blood. Their bodies are elongated, having a small chest, lean and lacking in muscular definition. Their legs are shorter and jointed differently than a normal humanoid and their limbs are also proportionally different than a normal humanoid; their humerus and thighs are the same lengths as their forearms and shins.

Their heads are unusually large in proportion to their bodies and they also have no hair anywhere on the body, including the face, and no noticeable outer ears or noses, but only small openings or orifices for ears and nostrils. They have a very small and very large mouths, no teeth, a light green tongue and large opaque black eyes with no discernible iris or pupil. Their hands have only 3 long finger and no thumbs, however their fingers are so long they can wrap around objects and use any objects like any other humanoid species. They seem to breathe a similar atmosphere that humans do and subsist on a diet of unknown worm and squid food.

Description
They seem to have a strict society focused on work and progress, with no apparent concern for hobbies and personal pursuits. Their architecture is spartan and purely functional - for instance, their bed (called a stasis chamber) is a sterile metal capsule with no mattress, blankets, sheets, or other pieces of bedclothes typically found in a normal human bed, and no discernible means of entertainment can be seen aboard Zeta. However, the aliens, in their own right, appear to have some degree of emotion since alien workers display obvious fear when confronted with armed assailants. In another notable case, the aliens are shown to have an unusual fascination with Giddyup Buttercup, as demonstrated in a captive recorded log onboard Zeta, of Sally being taken to the recording room and noticing a Giddyup Buttercup. She notes that upon her calling attention to it, the aliens become very excited, though she has no idea why they act this way.

They view other species as laboratory animals, worthy of preservation and storage at best and vivisection and experimentation at worst. They speak in their own language of high-pitched screeches and wails. As such, communication between humans and aliens is impossible. This isn't helped by the fact that, barring recording some brief biographical information, the aliens simply aren't interested in discussion.

They are incredibly advanced in their variegated technological fields, capable of spaceflight and technological feats equal to but often beyond that of even the most advanced human pre-War technology. They also possess technical faculties such as long-term cryostasis, powerful raygun, genetics, teleportation and holograms. However, they are totally dependent on technology, physically limited by their extreme use of technology. Because of this, they are physically fragile, lacking in raw strength, are ineffectual in melee-based combat, and don't possess especially protective armor and clothing.

Aliens typically wear spacesuits, the colour of the suit apparently indicating rank, and soldiers generally carry shock batons, disintegrators and atomizers. They prefer to attack their foes in large numbers, and tend to have guardian drones with them.

Encounters

 * In Fallout, the Vault Dweller can encounter a device based on alien technology (the Psychic nullifier) and a flying saucer with two alien skeletons.
 * In Fallout 2, the Chosen One can encounter two technologies based on alien technology, bio med gel and Skynet.
 * In Fallout 3, the Lone Wanderer can encounter a downed recon craft named Theta and a dead alien, and can be abducted by a mothership named Zeta.


 * In Fallout: New Vegas, the Courier can encounter a unnamed recon craft with two aliens and an alien captain around.

Crashed ships
Five alien ships are known to have crashed in the United States:
 * A flying saucer in special encounter in California (Fallout).
 * A recon craft named Theta in Capital Wasteland (Fallout 3).
 * Another recon craft that crashed and exploded on contact with the ground near the Lone Wanderer in the Capital Wasteland (Fallout 3).
 * At the Citadel, there is information on a terminal (in the A-Ring) about another ship of unknown type named Paladine that crashed in a heavily wooded area which the government was not able to reach.


 * A recon craft with three aliens near Horowitz farmstead in the Mojave Wasteland (Fallout: New Vegas).

Weapons
Firearms:
 * Alien atomizer
 * Alien blaster
 * Alien disintegrator
 * Atomic pulverizer
 * Captain's sidearm
 * Destabilizer
 * Drone cannon
 * Drone cannon Ex-B
 * Firelance
 * Small energy cell alien blaster

Melee weapons:
 * Electro-Suppressor
 * Shock baton

Ammunition:
 * Alien power cell
 * Alien power module

Turret:
 * Alien turret - turret which fire concentrated ball of electric energy.

Vehicle mounted:
 * Death ray - powerful raygun cannon equipped on mothership.

Robots and computers

 * Experimental weapons drone - experimental security robot armed with a drone cannon Ex-B
 * Guardian drone - security robot armed with a drone cannon
 * Support drone - maintenance robot

Vehicles

 * Flying saucer - small ship with a saucer-shaped body used for fast operations that houses 2 pilots. The only known flying saucer is the one that crashed in California.
 * Mothership - large ship dedicated to long-term space travel and study species. It's generally located in space. It houses an entire crew of aliens and is commanded by a captain. The overall shape of the ship resembles a colossal saucer with another small disc-shaped section attached to the bottom. Known motherships are Zeta and the unnamed mothership comes right after Zeta's bridge is captured by the Lone Wanderer.
 * Recon craft - small ship with a disc-shaped rear body used for stealth operations that houses only 1 pilot. Known recon craft are Theta, another exploded and sprayed in the Firelance event, and a possible unnamed in the Mojave Wasteland.

Medical

 * Abominations - biological weapons created from humans with alien DNA.
 * Alien biogel - ingestible curative gelatin-like liquid and accelerate organic tissue's regeneration processes gel.
 * Healing archway - care generator restoring health, removing all radiation, clearing any drug addiction and restoring crippled limbs.

Food

 * Alien squid food - strange squid-like creature with a long-term conservation.
 * Alien worm food - strange worm-like creature with a long-term conservation.

Device

 * Alien epoxy - advanced liquid repairing agent.
 * Alien homing beacon - teleportation beacon sent by a mothership to return quickly.
 * Drone control device - remote control for alien drones.
 * Force field generator - portable forcefield used for protective cover or blocking a passage.
 * Inertia suppression field - personal protection shield technology.

Miscellaneous

 * See Alien items.

Appearances
In Fallout and Fallout 2, they only appear in the form of skeletons. The crashed recon craft Theta appears in Fallout 3 with the first dead alien, and the aliens are the primary antagonists of the Fallout 3 add-on Mothership Zeta. They also make an appearance in Fallout: New Vegas if the player has the Wild Wasteland trait. If the player has the associated trait then they are spotted in the up most northern part of the map near Brooks Tumbleweed Ranch

Behind the scenes

 * The aliens resemble Greys, beings commonly described in alien abduction accounts and commonly depicted in 1950's science fiction that have come to represent the "stereotypical" alien.