Alien Aliens , known as Zetans by pre - War conspiracy theorists , are an extraterrestrial yellowish - green skinned humanoid race from an unknown planet . The only thing known about them is that they use their ability to travel space to probe other planets and species for information . Background . It is not known from what system or what planet they come from . They have orbited and observed the Earth with two known mothership s ( " Zeta " and an unnamed one ) at least since the 1600s in Earth ' s solar system , but humans had little real awareness of them and less evidence of their existence . Before the 1960s , only " crackpot " groups such as Quaere Verum believed in them , thinking that aliens existed but that evidence of their existence was covered up by a government conspiracy . However , after the mysterious disappearances ( abducted by aliens in " Zeta " in fact ) of the USSA space capsule Clarabella 7 and the pilot , astronaut Colonel Hartigan , during the 1960s , the aliens became recognized by national leaders . 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 suspicions . The pre - War United States government was said to keep its alien specimens and technology mainly in Area 51 ( such as a flying saucer that was later re - captured by aliens , but crashed in California probably during a flight sometime after the Great War , instantly killing the two alien pilots ) . The Brotherhood of Steel around 2161 and the Shi around 2241 have encountered the bodies of aliens or their spaceships . By extension , the Brotherhood of Steel in the Capital Wasteland have 72x alien power cell s 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 advanced human technologies were created by using alien technology , such as the AI project number 59234 , created in the 2050s , which manages the entire Sierra Army Depot Skynet , the device blocking telepathic and psychic commands , the psychic nullifier and probably the advanced accelerated organic tissue regeneration processes gel mostly used for brain bots ( robobrain , humanoid brain bot , think tank ) , and the bio med gel developed at the Boulder Dome . < section begin = " Fallout4 " / > Jack Cabot also suggests the presence of " ancient aliens " as a precursor to original human civilizations such as Assyria , that guided humanity to develop . His findings are enormously compounded by an ' artifact ' discovered by his father , Lorenzo Cabot , which granted him incredible abilities of telekinesis , ' immortality ' which could be replicated by extracting his blood and transforming it into mysterious serum , and incredible strength . Lorenzo ' s artifact itself utilized an ancient Egyptian scarab to focus the ordinary Gamma Gun into a powerful kinetic blast . In Jack ' s terminal notes , he speaks of a location his father may have relayed to him - Ubar - which is a legendary ' Atlantis of the Sands ' believed to have been located and lost somewhere in Arabia . < section end = " Fallout4 " / > It is also possible that the Zetans may have had some influence on the Great War , evidenced by a recording aboard Mothership Zeta . In this recording , a soldier ( or other military official ) of the United States is heard as he is attempting to resist the Zetans ' attempts to probe his mind for information , one subject in particular , the United States ' nuclear launch codes . This is purely based on speculation , as it is unknown whether or not the Zetans were successful in their attempts , or if they used the codes even if successful . Although we may never know for sure , the idea that the Zetans used the nuclear launch codes to " kick off " the Great War is possible . Biology . < section begin = " Alien biology " / > Aliens 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 . Aliens have no opposable thumbs , each hand instead having three long , tentacle - like fingers with large suction cups at each fingertip that allow them to manipulate objects . They breathe a similar atmosphere to humans , and ( at least those on Mothership " Zeta " ) subsist mainly on a diet of strange , alien worms and squid . < section end = " Alien biology " / > 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 supposedly impossible . However , linguistics specialist Holly Barrisford did make an attempt to communicate with the aliens during her abduction . Unfortunately , barring recording some brief biographical information , the aliens simply aren ' t interested in discussion . They are incredibly advanced in their various technological fields , capable of spaceflight and technological feats equal to , and often beyond , that of even the most advanced human pre - War technology . They also possess technologies such as long - term cryostasis , powerful rayguns , genetic manipulation , teleportation and hologram s . However , they are totally dependent on technology . Because of this , they are physically fragile , lacking in raw strength and ineffective in melee - based combat . Very few possess especially protective armor and clothing . Aliens typically wear spacesuits , the color of the suit apparently indicating rank , and soldiers generally carry shock baton s , disintegrator s and atomizer s . They prefer to attack their foes in large numbers , and tend to have guardian drone s with them . Crashed ships . Six alien ships are known to have crashed in the United States : 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 " " 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 . < section begin = " btsAlien " / > The aliens resemble , beings commonly described in alien abduction accounts . These aliens have been commonly reported since the 1950s . Later , the Greys became more mainstream when science fiction began depicting them . These kinds of aliens have come to represent the " stereotypical " alien . The name " Zetan " may refer to the star system " Zeta Reticuli " , a real - world star system seen in a number of science fiction stories , such as the " Alien " franchise . It was also rumored to be the origin of the aliens who allegedly abducted Barney and Betty Hill in 1961 , which was the first widely - publicized report of an alien abduction . < section end = " btsAlien " / >