Alien

Aliens are a type of creature, including those known as zetan aliens.

Background
After the mysterious disappearance of the USSA space capsule Clarabella 7 and the pilot astronaut Colonel Hartigan suspicions arose, and in 2062 the existence of aliens became internally recognized by the government. Alien technology was used to develop Skynet.

The Capital Wasteland Brotherhood of Steel have alien power cells in the Citadel's armory and the Brotherhood Outcasts also have some at Fort Independence. The Enclave has an alien blaster and some alien power cells in the armory of the mobile base crawler at Adams Air Force Base.

They possess technologies such as long-term cryostasis, guns, teleportation and holograms. They carry shock batons, disintegrators and atomizers, and use guardian drones.

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 zetan. In the Mothership Zeta add-on, the Lone Wanderer can be abducted by zetans at the alien crash site and taken aboard a spaceship named Mothership Zeta.
 * In Fallout 4, the Sole Survivor can encounter an alien spaceship falling from the sky shortly after reaching level 20. Companions have unique commentary upon observing the crash. The crashed UFO is always located east of Oberland station. Following green bloodstains will lead the Sole Survivor to a hostile injured alien which can be looted for the alien blaster pistol. Animatronic aliens can also be found in Nuka World, modeled after zetans and utilizing their alien blaster weapon for lethal and non-lethal purposes.
 * In Fallout 76, the player character may randomly encounter aliens, the Flatwoods monster, and find alien blaster pistols. There are also alien props able to be located in Van Lowe Taxidermy.


 * In Fallout: New Vegas, with the Wild Wasteland trait, the Courier can encounter an unnamed recon craft with two zetans and an alien captain nearby.


 * In the Creation Club quest Over the Moon, the Sole Survivor encounters a second alien craft abducting a brahmin, along with two hostile aliens with unique weapons.

Crashed ships
Six alien ships are known to have crashed in the United States:
 * A flying saucer in a special encounter in California.
 * A recon craft named Theta in the Capital Wasteland.
 * Another recon craft that crashed and exploded on contact with the ground in a random encounter near the Lone Wanderer in the Capital Wasteland.
 * At the Citadel, there is information on a terminal (in the A-Ring) about another ship of unknown type codenamed "Palandine" that crashed in a heavily wooded area near Hagerstown, Maryland which the government was not able to reach.
 * A recon craft with three aliens near Horowitz farmstead in the Mojave Wasteland.
 * An event in which a UFO crashes to the ground south of the Beantown Brewery in the Commonwealth.

Vehicles

 * Flying saucer - Small ship with a saucer-shaped body used for fast operations that houses two pilots. The only known flying saucer is the one that crashed in California.
 * Mothership - Large ship dedicated to long-term space travel and the study of other species. It's generally located in space. It houses a large 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 which arrives 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 one pilot. Known recon craft is Theta, another which exploded and sprayed in the Firelance event, and a possible unnamed craft in the Mojave Wasteland.

Food

 * Alien squid food
 * Alien worm food
 * Alien epoxy
 * Alien homing beacon
 * Drone control device
 * Force field generator
 * Inertia suppression field
 * Misc 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 Wild Wasteland trait is active. If this is the case, then they are spotted in the northernmost part of the map near Brooks tumbleweed ranch. In Fallout 4 they appear during an event in which a UFO crashes to the ground south of the Beantown Brewery in the Commonwealth. In Fallout Shelter they appear during the quest Humans Like Us, where they use optical camouflage to look like male human beings.

Behind the scenes
 The zetan aliens were designed to resemble "Roswell grays," stereotypical representations of aliens in pop culture and described in alien abduction accounts. 