The Praetomorph,[1] also known as the Planet 4 Xenomorph, was a variant of the species Xenomorph XX121 that attacked the crew of the USCSS Covenant. The species originated on Planet 4 as a result of genetic experimentation carried out by David 8.


The Praetomorph was created by the android David 8's experiments using the Chemical A0-3959X.91 – 15 pathogen as a catalyst on tissue samples harvested from Elizabeth Shaw, deceased Engineers, and Neomorphs spawned from the native species of Planet 4. Over the course of a decade, David continued to perfect his designs until he created the first Ovomorphs, which contained Facehuggers that implanted two members of the Covenant's crew, who later birthed the first versions of the Xenomorph on Planet 4. After hijacking the USCSS Covenant, David transmitted the records of his experiments to the Weyland-Yutani Corporation, expressing the intent of continuing his experiments using the settlers and surviving crew and creating a Queen that would change everything.


After Covenant captain Oram shot down a Neomorph, an enraged David tricked the former into following him to his workshop where he had been experimenting on the pathogen to create the perfect organism. David brought the captain further down, revealing a chamber filled with large eggs. Oram was unaware of how they functioned until it was too late, as a Facehugger leapt out of its egg and viciously latched onto his face. Sometime later, Oram awakened and had a brief discussion with David about their beliefs. Seconds later, a Chestburster ripped its way out of his chest, killing him while David looked on and smiled proudly at the newborn Praetomorph.

Sergeant Lopé and Cole discovered the workshop in search of Oram; Cole found Oram's body, as well as another Facehugger. It attacked Cole and latched on to his gun; Cole managed to throw it off and shot at it, though it dodged his gunfire and instead ran toward Lopé. As the two tried to locate the creature, it attacked Lopé and latched onto him. Cole used a knife to cut it off, with the resulting acidic blood burning Lopé's cheek. As Cole tried to bandage the wound, Lopé noticed the Praetomorph watching them from an overhead shaft. Panicking, Lopé got to his feet and ran as the alien lunged on Cole, pinning him to the floor and killing him.

The Planet 4 Xeno

The Praetomorph pursued the crew of the Covenant and discovered them attempting to escape on its cargo lifter. Although it managed to get on board and endured some serious injuries, it was duly defeated by chief terraformist Daniels.

The crew took Lopé to the medical ward on the Covenant. Subsequently, ship computer MU-TH-UR contacted Daniels and informed her of an unidentified lifeform present on the ship. Daniels and pilot Tennessee headed to the medical ward and found Lopé dead with his chest burst open; the Facehugger from earlier had managed to impregnate him.

The already-mature Praetomorph roamed the ship and ambushed Ricks and Upworth while they showered together, killing Ricks via headbite before murdering Upworth. Following this, the creature was lured to the Terraforming Bay by Daniels and Tennessee, where they trapped it inside one of the Terraforming Trucks and attempted to eject it. However, the truck's deployment winch was jammed by a JCB skid-steer that broke loose of its moorings, and Daniels had Tennessee release a second truck to eradicate the blockage. Given time to escape, the Praetomorph broke out of its prison and attempted to perform one more feat to return to the ship. The second truck impaled the alien and sent it flying out of the Covenant to its death.


While virtually identical to Xenomorph XX121, this version possessed notable differences that set it apart from its mainstream cousins. Notably, it lacked any biomechanical features and its limbs were longer, thinner and skinless, with exposed muscles and blood vessels and gaps appearing in its armpits. The shoulders and dorsal spines were noticeably different, being smaller and narrower. This Xenomorph variant also had a thinner, sleeker tail ending in a small barb.

This variant's egg is slightly different in overall shape
The opening and organic insides are also notably different.

The differences in the Drone also extended to its Chestburster form, as well as the Facehugger to a lesser extent. Other than these differences, the Praetomorph greatly resembled the Xenomorphs from the Derelict on LV-426.

Like Xenomorph XX121, this variant possessed an inner pharyngeal jaw. This appendage was capable of shooting from their mouth like a piston, with sufficient power to smash through bone and metal.[2][3] In fact, a known common tactic used by its cousins to eliminate prey was to restrain the victim with their hands, immobilizing them, before killing them with a precision jaw strike to the head, piercing through the skull and penetrating the brain; this form of attack was colloquially known as a "Headbite".[4]

The most unique aspects of the variant were its incredible resilience and determination. When aboard the cargo lifter Tennessee was flying, one received a full blast from one of the ship's thrusters but continued its hunt despite being bathed in flames. Another proved its relentlessness by breaking out of the truck in which Daniels trapped it and running across the falling vehicle to get back to the Covenant.

Overall, its growth rate was incredibly fast, as it could be seen visibly growing after only just emerging from its host. Not long after this, it was next seen as a fully mature adult.

The Praetomorph could see almost as clearly and detailed as humans, albeit with "floaters" throughout its vision.

Evolved form

The Praetomorph further evolves into a Stalker.


The Praetomorph possessed more or less the same basic intelligence but seemed to be unable to differentiate between living or inorganic objects when they were moving, as the first Praetomorph got itself killed while attacking the cargo lifter's moving crane claw by jumping into it, which resulted in it being crushed to death, and the second Praetomorph attacked the video feed of David.

Life Cycle

See: Xenomorph life cycle


Main article: Ovomorph (Planet 4)

Like all members of the species Xenomorph XX121, the Praetomorph has a complex and parasitical life-cycle that requires a host. The process itself is actually completely identical with the creature having its beginnings in an Egg of similar shape to its cousins, though with notable differences in shape.


Main article: Facehugger (Planet 4)

Once the egg opens, a Facehugger will emerge, attach itself to the face of a host, and immediately implant an embryo, with seemingly even a brief moment of contact being able to ensure impregnation. Though the removal of the Facehugger is less difficult compared to the mainstream variant, as it has less potent acid blood, the Planet 4 Facehugger is able to counteract these setbacks by seemingly being able to implant a host within seconds of attachment.


The Chestburster uses its shape to burst its way out of its host, and once it emerges, it undergoes an almost immediate transformation. Due to this species accelerated growth, the Chestburster itself seems to be born almost fully developed, similar to the Chestburster that emerged from an animal on Fury 161.


  • The name Praetomorph was developed by the creators of Alien: The Roleplaying Game from the term "Protomorph" (previously used during the conceptual stage for the Deacon in Prometheus[5]) combined with the prefix "prae", taken from the Plagiarus praepotens mutagen described in the novel Alien: The Cold Forge.
  • According to Ridley Scott's director's commentary, the Praetomorph is able to regenerate from would-be fatal injuries like being crushed and dismembered, making it virtually indestructible.
  • Its design was based on that of an écorché, while its movements were based on those of a praying mantis and a baboon.[6][7]
  • The Praetomorph has a human skull underneath its smooth dome, something the original Xenomorph (from Alien) also featured.
  • The exact origins and nature of the Praetomorph have been widely debated amongst fans, with some believing David is responsible for the Xenomorph XX121 species, while others believe he merely recreated something that the Engineers created. The reason for this debate is due to evidence of the existence of a Xenomorph-like species, depicted in a mural shown inside the Engineer Ship explored by the Prometheus crew. It is still unclear if David saw the mural due to the fact that in the film it is never specified, therefore creating a debate between some fans on whether this had any influence in David's experiments or not.
    • In addition to the belief that David is responsible, some fans have nicknamed the Covenant variant a Protomorph, believing that it is the precursor or progenitor to the original species.
    • In the novelization and early drafts of the script, the Xenomorph XX121 species was created by the Engineers, and David's Praetomorph variant was created in an attempt to replicate them. The final film lacks this revelation, with comments by Ridley Scott indicating that the decision was made late in development to have David be the sole creator.
  • In the novelization, the Xenomorph is described as possessing a biomechanical mesoskeleton, but in the film itself, the Praetomorph lacks biomechanical features, stated in interviews to have been a deliberate design decision. 
  • The Planet 4 variant appears to have a similar life-cycle speed to those in Alien vs. Predator. It also appears that the parasite stage is capable of implanting a host within seconds of attachment. Both have caused criticism amongst fans.
  • The Praetomorph's motion capture was provided by Javier Botet, a Spanish actor with Marfan Syndrome who is mostly known for his roles in REC (2007) and Mama (2013).[8]
  • There are notable differences between the film Praetomorph and the NECA figure: the NECA figure has shoulder tubes and the tubes on the back of the figure are more upright. The film Praetomorph lacks shoulder tubes and the back tubes are more separated and bent over. That's because NECA has been provided with concept art by Colin Shulver.
  • One of the Minimates figures of the Praetomorph is named the "Goran Xenomorph", this is a reference to the actor who portrayed the Praetomorph, Goran D. Kleut.




Concept art



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