Alien

While there is some evidence of the existence of alien life forms, it is very scarce. Until the events of the Fallout 3 add-on Mothership Zeta, there was no record of direct contact between humanity and the creatures.

The Brotherhood of Steel and Shi have encountered the bodies of alien life forms or their spaceships, as did the pre-War United States government, which kept its alien specimens mostly in Area 51. By extension, the Enclave and Brotherhood Outcasts also have access to alien technology; Alien Power Cells can be found at Fort Independence and in the armory of the Enclave's Mobile Base Crawler. They can also be found in the Citadel's armory (if you choose to destroy the Citadel during Who Dares Wins).

Crashed ships
Four alien ships are known to have crashed in the United States:


 * An alien ship in special encounter in California (Fallout).
 * Recon Craft Theta in Capital Wasteland (Fallout 3).
 * Another alien ship can explode over the head of the Lone Wanderer in the Capital Wasteland during a special encounter although the cause of the catastrophe is unknown (Fallout 3).
 * At the Citadel, there is information on a terminal (in the A-Ring) about another ship that crashed in a heavily wooded area that the government was not able to reach (Fallout 3).

Weapons
Firearms:
 * Alien Blaster
 * Firelance
 * Disintegrator
 * Alien Atomizer
 * Drone Cannon

Explosives:
 * Cryo Grenade

Melee weapons:
 * Shock Baton

Ammo:
 * Alien Power Cell
 * Alien Power Module

Robots and computers

 * Experimental Weapons Drone
 * Guardian Drone
 * Support Drone
 * According to its own (potentially unreliable) records, the Skynet computer was created based partly on alien technology. (Fallout 2)

Vehicles

 * Mothership Zeta - large alien vehicle
 * Recon Craft Theta - small alien vehicle

Other

 * Alien Epoxy - Alien repairing agent.

Appearances
Crashed alien ships appear in Fallout 3. Alien Blaster appears in Fallout 3. Aliens also appear and abduct the player in the Fallout 3 add-on, Mothership Zeta. In the add-on, the aliens are presented as malevolent creatures that seem to view humanity with contempt and will gladly vivisect their test subjects or keep them in cryogenic storage after torturing them for information. The aliens themselves seem to have their own language and cannot be understood by the player in any way. Considering the size and weapons capability of the mothership, it is plausible that the aliens were planning an invasion of Earth.