The Engineers, also called Pilots, Space Jockeys, Ossians or Mala'kak, are among the oldest extraterrestrial life. Due to their civilization being, presumably, billions of years old, they have no clear origin but possess among the most advanced technology in the galaxy. This technology has made them masters of genetic engineering, seeding many primordial celestial bodies with life.
Biology and Appearance
As seen in Prometheus, the Engineers are extremely pale-white, hairless and humanoid, with two arms and legs, and said to have staring, "dead seeming" eyes. Their veins visible underneath the skin. Their pupils are in the shape of oblong plus-symbols. The species was once thought to have telepathic powers, but the Weyland-Yutani Corporation scientists have found this not to be true, from certain information deciphered off the logging device. The distress signal picked up by the Nostromo was an acoustic beacon giving out a signal every 12 seconds. The Engineer encountered in the derelict spaceship on Acheron was equipped with a biosuit that made it seem like a creature that had what was believed by the crew of the Nostromo to be a trunk (or breathing apparatus). The trunk, extending vertically down a broad chest, was thought to be where the "space jockey" breathes. The 'mouth' was present under the beginning of this trunk and seemed to have two mandibles (or 'alien tusks') at the sides of the mouth, though this was revealed in Prometheus to simply be part of the suit. The arms are visible to its sides and the suit appeared to have been grafted into its seat. The lower body of the creature was obscured by its seat and was not observed. The suit resembles a '8" foot tall humanoid elephant.
They are humanoid and look just like human beings except when it comes to size, eyes and hair. The Engineers seem to possess no body hair, including eyebrows and eyelashes, their lips are as pale as the rest of their skin, and the eyes are almost completely black. Their size, ( 7'0") gives them enormous strength relative to a human. Their behavior is almost unknown, and the only example of a living Engineer seen so far in the series occurs in Prometheus.In this short time we learn that the Engineers were plotting a course for Earth, and were planning on using the assorted dangerous organisms in the cargo hold as weapons. All but one of the Engineers on LV-223 were killed by their own cargo, which were too unwieldy to control, despite having been created by the Engineers themselves. It's unknown why the one Engineer remained in cryo-sleep while the rest of his kind on LV-223 were killed in the incident at the LV-223 outpost.Their homeworld is unknown, but they are known to be capable of colonizing worlds similar to their own, and for being able to terraform or create a breathable atmosphere in an otherwise inhospitable environment. Their technology is incredibly advanced, and their knowledge of the cosmos, as evidenced in Prometheus, is vast, if not complete. If the actions of the Engineers in Prometheus are any indication, they appear to be wholly inimical to human life.
Cuneiforms, Hieroglyphs and Language
The Engineers' writing system is strikingly similar to Mesopotamian cuneiforms that can be found in the middle-east, and their hieroglyphs are identical to what is found in Egypt, Mesoamerica, and other areas on Earth. Not much is known at the moment involving whether they are responsible for giving humans an extinct language which has not been spoken for five thousand years or more on Earth or not, but it is currently being spoken and written by the Mala'kak and seems to be their language.
Relation to the Xenomorphs and other races
Little is known of this race. The principal theory of their connection to the Xenomorphs, which was mentioned briefly by Ridley Scott in his director's commentary for the first Alien DVD, is that the Engineer ship in Alien was a "bomber" and that they used them as biogenic weapons to fight an ancient war against an unknown foe. There is some evidence to support this, such as the Xenomorph's biomechanical nature. Alien eggs were believed to be used as "bombs" on an enemy planet and then the Xenomorphs would proceed to kill the entire population as they spawned. In Prometheus, it is shown that a lone Engineer was possibly responsible for the creation of the human race. He sacrificed himself as his people left the empty Earth, drinking chemicals that dissolved him and changed his DNA to the planet's first micro-organisms. Humanity soon developed, making the Engineers the ancestors of the human race. As such, human DNA and Engineer DNA are virtually identical. The lone Engineer's reasons for doing this is unknown, though it seems his race did not hold any positive regard for their descendants. Dozens of cargo ships carrying the weaponized Black Liquid were set to launch for Earth to release the pathogen and let it wipe out humanity; only to see the Engineers somehow lose control of their intended weapons and perish. The crew of the USCSS Prometheus believed that the abandoned planet they explored was an outpost for weapons engineering and development, lending credence to the theory that the Engineers created the Xenomorphs (or perhaps more specifically, the black goo that led to the Trilobite) for war and genocidal purposes. It was also noted by the crew of the Prometheus that the Engineers on LV-223 had been dead for around 2,000 years. This has led fans to speculate that up until about 2,000 years ago Engineers were on good terms with humans, but a specific event occurred which caused them to become hostile towards humanity. This explains the cave drawings "inviting" humanity to track them down. It is also possible that the Engineers had seeded the Earth with human life to create a "breeding ground" for Proto-Xenomorphs for military purposes.
The Engineers are clearly a technological superpower, space-faring race of advanced age. They are known to carry in their cargo a particularly deadly bioweapon: a form of black liquid released from vases, which is most likely a mutagen. This mutagen is so refined that it has the propensity to create lifeforms, namely the Trilobite. The Engineers can also ingest a similar liquid, which causes their bodies to disintegrate and be reduced to the basest forms of their DNA, useful for terraforming and directed panspermia. The cargo hold of the Engineer ship in Alien was filled with Xenomorph Eggs (the first stage in the Xenomorph life cycle), which were held in stasis beneath a blue electrical mist. It has been speculated by fans that the Engineers are the creators of the Xenomorphs because of the similarities in design between the spacecraft and the biomechanical Xenomorphs. The novelization by Alan Dean Foster, on the other hand, states that the Engineer race found them on LV-426, and there has been no conclusive evidence shown in the feature film series supporting that the Engineers created the Xenomorphs. Clearly, however, the Engineer race have advanced technology, leaving open the possibility that they had a hand in the Xenomorph's creation. Director Ridley Scott also makes note that he would like to make "an Alien 5 or Alien 6" where the audience would be privy to the home planet of the Xenomorphs and learn more about the Engineers, but makes no reference to whether this is the same planet that the Engineer race hails from.
The Derelicts are a type of bioship from an advanced race (the Space Jockeys). It is organic in appearance, and it shows signs of being partially fossilized; though it is still functional, since it is still sending out an automated radio transmission. The dead Pilot is also fused to the command chair on the ship's bridge equivalent. The film Prometheus later reveals that the suit is a part of the chair and a pilot is not fused to it but merely inside a suit connected to the chair which folds over the pilot. The Derelict is a large, asymmetrical, wishbone-shaped craft, with a thickened central section between two horns, which bend upwards. It has numerous tunnels that go off to many places. It has three large openings near ground level between two horns, leading into the ship's interior. It is through one of these openings that three of the Nostromo crew members (Captain Dallas, Navigator Lambert, and Executive Officer Kane) entered the ship. The interior of the Derelict resembled more of a living organism than a spacegoing vessel, with skeletal walls, circular gangways and steep passages. One interesting aspect of the ship is that exactly what part of the ship seen by the Nostromo's crew goes completely unexplained. It would seem to be the bow, or front, because the Space Jockey is apparently the pilot but this is uncertain. The exterior of the ship looks almost like the stern (back-end) of a ship that has hit the ground and buried its nose in the dirt. Whichever theory one chooses to accept will also dictate which backstory the viewer will accept.
The Black Liquid was a pathogen manufactured by the Engineers for war and genocidal purposes. The Black Liquid is an extremely lethal pathogen composed of millions of small micro-organisms. Once exposed to another organism, the pathogen begins mutating its host. The host becomes extremely aggressive and seemingly mindless as it attacks any living thing in sight. Geologist Fifield was exposed to the liquid during the Prometheus' expedition of LV-223, mutating his appearance and causing him to attack his fellow crewmembers. He was also extremely resistant to physical injury, being able to withstand multiple gunshots. It took several shotgun blasts and being scorched with a flamethrower to finally kill him. He was also able to survive on LV-223's surface without a helmet for extended periods of time (despite its heavy carbon monoxide content, capable of killing a human within a few minutes), showing superhuman endurance and possibly modifications to his respiratory system. The liquid also mutated several tiny worms found in the Engineer ship, turning them into the aggressive Hammerpedes. The Hammerpedes exhibited acidic blood and the ability to regenerate lost body parts, though the latter is an ability commonly found in Earth worms and thus may not be caused by the black liquid. However, the regeneration of Hammerpedes is much faster than that of Earth worms, suggesting that the Black Liquid can enhance a host's natural abilities. Holloway was also exposed to the pathogen and began mutating before Meredith Vickers killed him to prevent the pathogen from coming aboard the Prometheus. The pathogen appeared to affect his reproductive system, as prior to his physical mutation (while carrying the pathogen), Holloway had sexual intercourse with his girlfriend Elizabeth Shaw, impregnating her with a Trilobite. It is not known if his sperm was mutated causing an abnormal conception or if he was simply carrying a Trilobite that moved into Shaw, though the latter seems more probable given that Shaw was sterile. Whether Trilobites prefer to move into female subjects or if Holloway would have naturally given "birth" to the Trilobite is unknown. Although Shaw was exposed to the infected Holloway and had intimate contact with him, she was not infected with the liquid and only received the Trilobite embryo. This suggests that the Black Liquid itself is not sexually transmitted, although it can affect the host's reproductive systems. The Trilobite carries a lone Deacon egg for impregnation. It appears the black liquid is intended to mutate its target populace, turning the afflicted against one another and mutating indigenous lifeforms into hostile xenoforms before finally unleashing the Deacons on the weakened population. However, the full effects of the pathogen are unknown and may vary from subject to subject, as shown by Holloway and Fifield. Infected hosts seem to share some characteristics with the Xenomorphs, such as unnatural hostility, endurance and, in some cases, acidic blood.
The Hammerpede is formed when the Engineers' urns spill Black Liquid on the indigenous worms of LV-223. Whether they can be formed from other species of worm on other planets is unknown. The Hammerpedes are very similar to real-life worms, but they are much larger. They were pale in color and had serpent-like bodies up to 4 feet long. Their crests are very similar to those possessed by cobras (which is why they are sometimes referred to as Cobrabursters or Cobraliens). These crests could be folded in and out around the creature's "head". Their "head" was similar to that of a Facehugger, and they possessed the same acidic blood. They possessed incredible strength, able to break bones rather easily as was demonstrated when Fifield attempted to remove one from Millburn's forearm. They also possessed the ability to rapidly regenerate severed parts in a matter of seconds as shown when Fifield attempted to decapitate one, only to have its head quickly regenerate.
The Trilobite is the result of the Black Liquid infecting Holloway and his impregnation of Elizabeth Shaw. It is not made clear if the creature was conceived by their intercourse or if the infant creature merely moved into Shaw from the infected Holloway. It is unknown how the creature gets out of its host "naturally", as Shaw removes it prematurely; however its exaggerated movements prior to this suggest that it "bursts" like Bellybursters, emerging from the host's abdomen. As an adult, it resembles an extremely large Facehugger (even larger than Engineers), but with many differences. It is comprised of many large tentacles which are strong enough to subdue the 8-foot tall engineer and also has six smaller tentacles that shoot out around its mouth. Unlike a facehugger, it does not leap onto a victim's face but instead grabs it with its tentacles and attempts to subdue it long enough to impregnate it, after which it settles its considerable body mass on top of the host's body. At the centre of its body is a large toothed mouth inside which resides a large feeding tube used to impregnate its host. During impregnation, hosts lose strength and fall unconscious, like normal facehugger victims. The impregnation process seems to be the same as the facehugger's, but when a Trilobite impregnates a host, it results in a Deacon. The Trilobite also dies after it impregnates a host, much like facehuggers. The Trilobite lacks a tri-lobed body and bears no resemblance to the prehistoric creature of the same name.
The Deacon, also known as the Proto-Xenomorph, is a Xenomorph-like creature formed following the Trilobite's impregnation of an Engineer. It is important to note how the birth of this creature is different from the majority of Xenomorph births, as it appears to be a very basic yet humanoid form of the human-spawned Xenomorph. The fact that it spawns almost fully developed makes it quite unique compared to Xenomorphs seen in the series - though the Dog Alien chestburster had arms and legs upon bursting. Unlike Xenomorph chestbursters, which "punch" their way out using the front or top of their heads, this creature used the sharp back end of its head to tear a way out. Also unlike Xenomorphs, it does not have an inner jaw and instead has a human/Engineer tooth structure and gums. Its "inner jaw" is merely an extra jaw that protrudes a short distance but is much larger and more unwieldy than a Xenomorph's inner jaw. Whether or not this "inner jaw" can be used as a weapon is unknown.