Zetan aliens

Zetan aliens are an extraterrestrial yellowish-green 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
The origins and background are completely unknown. What can be deduced is that the alien ship “Zeta” has been in the earth's orbit since at least the time of feudal Japan, given the fact that one of its abductees is a samurai. The aliens aboard the ship appear to be scientists, studying abducted humans as well as other creatures such as super mutants.

Organization
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 beds (called stasis chambers) are sterile metal capsules 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 case, the aliens are shown to have a 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, verbal 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 rayguns, genetic engineering, teleportation and holograms. However, they are totally dependent on technology and are physically limited by their extreme use of it. 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 color 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.

Military
Due to their frail bodies, the zetans aboard Zeta generally rely on guardian drones do most of their fighting. However, certain zetans will utilize personal shields and rifles, implying that there are combat-ready members among their ranks. The most powerful known weapon in their arsenal is the death ray underneath their ship.

Weaponry
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 the 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 house two 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 the Zeta bridge is captured by the Lone Wanderer.
 * Recon craft - small ship with a disc-shaped rear body used for stealth operations that house only one 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 aliens 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 - beacon teleportation 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
Zetan aliens appears in Fallout 3, its add-on Mothership Zeta, Fallout: New Vegas, and Fallout 4. A Zetan craft model appears in the trailer of Fallout 76.