The origin of the zetan aliens is largely unknown, but throughout much of human history, the zetans have abducted and collected humans, their creations, and other creatures from Earth for study, cryogenic preservation, and experimentation. At some unknown point, the zetans arrived to Earth from an unknown star system on at least two known motherships to study the Earth, one known as "Zeta" and another unnamed one.
They have continuously abducted humans and other creatures from Earth, and also collected their technology. It was not until the abduction of Colonel Hartigan and the Clarabella 7 capsule, that their influence became felt by modern society, with groups such as Quaere Verum formed to reveal the truth about them, though Quaere Verum was widely regarded to be a crackpot conspiracy group by the public. Quaere Verum attempted to use the MPLX Novasurge, a prototype plasma pistol somehow recovered by the group from the government, as proof that the U.S. government had been using alien technology, though the weapon was later recovered by the zetans themselves, while the group itself was dismantled by the federal government for their role in stealing the weapon. At this point, it was believed by many that the U.S. government (and by extension, the Enclave) had based much of their technology off of alien technology. Everyday citizens also had some awareness of the zetans, given that some comics featured images of the zetans on their covers, and mentioned them by name.
In late pre-War West Virginia, the zetans operated through a network of zetan agents who captured individuals in the wilderness around the town of Flatwoods for experimentation. One such person was the Assistant Chief Executive Officer of Vault-Tec, who was inspecting the construction of Vault 76 sometime between 2064 and 2069. These alien agents were often spotted and reported upon by Flatwoods locals (some of which claimed to have been abducted), though local law enforcement did not take the sightings seriously. The zetan agents were dubbed the "Flatwoods Monster" by the locals and the media. These zetan agents continued to operate in Appalachia at least up until 25 years after the Great War. The Enclave also maintained a research facility in Appalachia where they apparently held three zetan bodies and studied them.
In other places across the pre-War United States, up until shortly before the Great War, the zetans continued to abduct humans. In 2041, they abducted the Professor of Anthropological Archaeology at Banfield College, Humboldt, Oregon. Other known abductees included a U.S.S.A. linguistics specialist, a U.S. senator and someone within the White House who had the codes needed to launch the entirety of the U.S.'s then-currently-armed ICBM nuclear weapons. During the Reclamation of Anchorage, Alaska (as part of the Resource Wars), somewhere between 2066 and 2077, numerous U.S. Army personnel were abducted from Alaska by the zetans, including a U.S. Army combat medic and his entire unit.
After the Great War, the zetans began abducting, and then studying and experimenting on, the new creatures from across the American wastelands (especially from the Capital Wasteland), including super mutants, feral ghouls, brahmin and many others. They also abducted members of the new groups of people formed after the War, including raiders and slavers. The "Flatwoods Monsters" also continued to operate in Appalachia for at least 25 years. Other groups across the wastelands seem to have had some awareness of (and some level of contact with) the zetans, because as of 2277 in the Capital Wasteland, the Brotherhood of Steel, Brotherhood Outcasts, and the Enclave had alien power cells in their respective armories.
Sometime around 2277, the Lone Wanderer encountered an alien signal that led them to a downed zetan recon craft known as Theta. On approach, they were abducted via a tractor beam onto Zeta. From there, they were experimented on and then placed in a containment cell, where they joined with several other abductees, including the aforementioned slaver, combat medic, samurai and cowboy, as well as a young pre-War girl, in order to take over the ship and find a way back to Earth. The crew fought their way through Zeta, destroying its generators (therefore crippling it) and then fighting all the way to the zetan captain's cabin. After slaying the captain, the crew took control of the ship and engaged in a final showdown with the other unnamed mothership. After destroying the other mothership, the crew went their separate ways, with the combat medic and young girl staying aboard the ship, and the rest leaving back to Earth.
Zetans are diminutive, hairless, yellowish-green-skinned humanoids with short, wiry limbs and green blood. Their heads are disproportionately large, with round, heavy-lidded, solid black eyeballs with no discernible iris or pupil; a thin, toothless mouth with green tongue, and two pairs of small holes where ears and nostrils would be. Zetans have no opposable thumbs, each hand having three long, tentacle-like fingers with large suction cups at each fingertip that allow them to manipulate objects. They are physically fragile, and rely heavily on advanced weaponry, robotics, and energy shielding to circumvent this weakness.
The zetans 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 zetans, in their own right, appear to have some degree of emotion because 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. The Lone Wanderer can also encounter what appears to be a sacrificial shrine to Giddyup Buttercup, where there is a large circular chamber, with the animatronic horse in the center surrounded by several human corpses.
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 is not helped by the fact that, barring recording some brief biographical information, the aliens simply are not 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 possess technologies such as long-term cryostasis, energy forcefields, 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 and ineffective in melee-based combat.
Due to their frail bodies, the zetans aboard Zeta generally rely on guardian drones, support drones and automated turrets to do most of their fighting. However, certain zetans appear to be combat ready soldiers, utilizing personal forcefields and forcefield generators for defense, atomizers and disintegrators for ranged combat, and shock batons for melee combat; all of their weapons are energy based. They also rely on support technology such as healing gels, weapon repairing epoxies, advanced healing archways and teleportation matrices. Lastly, they appear to employ genetically engineered zetan-human hybrids, known as abominations, as living weapons.
The bulk of their military capacity comes from the deathrays mounted on their motherships, which have payloads comparable to nuclear weapons. These motherships have energy shielding and are spaceflight capable. Motherships also maintain a hangar with a fleet of zetan-piloted recon craft.
Zetans have different color jumpsuits that appear to indicate rank, and they all seem to answer to the captain of their respective mothership. They also have civilian noncombatant support personnel, known as "workers," who perform maintenance, custodial, and research duties.
Their infantry tactics involve placing automated defenses in strategic locations, and relying on swarm tactics and advanced personal weaponry and defense systems to gain the upper hand on opponents. They also make use of the teleportation matrices across the mothership to instantaneously transport soldiers from one side of the ship to another.
Similar to the the Institute's Molecular Relay, Zeta possess a series of teleporters known as a teleportation matrix. They allow access between areas of the ship, as well as to and from beacons that can be deployed to the surfaces of planets.
Zetans possess an advanced understanding of cryostasis, to the point they maintain a specialized cryo lab aboard Zeta dedicated to keeping their various abducted subjects stored between experimentation and interviews. This storage was seemingly capable of keeping its subjects alive healthily for centuries, though it was not without risk. Under certain conditions, it can lead to the subject expiring upon being thawed. Colonel Hartigan became a victim of such conditions upon being thawed by the Lone Wanderer.
Zetans utilize holographic technology.
Robots and computers
- Experimental weapons drone - experimental guardian drone armed with a drone cannon Ex-B
- Guardian drone - security robot armed with a drone cannon.
- Support drone - maintenance robot capable of limited melee combat.
- Automated turret- a mounted automated energy weapons turret.
- 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, 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 unnamed craft that exploded in mid-air in the Firelance event, and another unnamed craft hovering in the Mojave Wasteland if Wild Wasteland is taken.
- UFO - small, single pilot ship is found at the UFO crash site within The Commonwealth between Beantown Brewery and Vault 81. The pilot survives the crash and relocates to a nearby cave.
- Abominations - biological weapons created from humans with zetan 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.
- Alien squid food - strange squid-like creature with long-term conservation.
- Alien worm food - strange worm-like creature with long-term conservation.
- Alien epoxy - advanced liquid repairing agent.
- Alien homing beacon - a homing beacon that allows one to return to a mothership to return quickly via teleportation.
- 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.
- See alien items
- Fallout 4 loading screens: "If the conspiracy theorists are to be believed, Earth has been visited by an alien species on several occasions. These "Zetans" are said to be armed with powerful energy beam weapons that can completely disintegrate enemies."
- Amplified Alien Blaster description: "This much power is usually reserved for a Zetan cruiser."
- Fallout 3 Official Game Guide Game of the Year Edition: "Once thought to be covered up by a government conspiracy and believed only by “crackpot” groups such as the Quaere Verum, evidence of extraterrestrial life can be traced back throughout human history, but became nationally recognized after the mysterious disappearance of the Clarabella 7 space pod during the 1960s Space Race. It is said that Alien technology was the basis of many of the Enclave's more exotic and impressive weaponry and robotics, and even toy manufacturers such as Wilson Automatoys weren't immune to these accusations. Recently, after the discovery of an Alien body in Fort Bannister, the shocking truth was revealed. The Aliens are not only real and alive, but they’re back. And they’re pissed."
- Fallout 3 Official Game Guide Game of the Year Edition p.110 "A secretive prototype to the Enclave’s Plasma Pistol, the Novasurge functions in a very similar manner, and proves a conspiracy theory you long suspected. There are other bonuses too; the MPLX Novasurge inflicts more than three times the damage of a Plasma Pistol, with a bigger Crit % Mult too. Unfortunately, it is heavier and uses ammunition twice as quickly. Repair it using Plasma Pistols. It is found in a safe in the Debris Pile after you unlock it by hacking Reid Underwood’s Terminal inside the Mothership Zeta Cargo Hold [MZ2.11]."