Native to a planet dubbed "Xenomorph Prime", these beasts are an extraterrestrial, endoparasitoid species with multiple life cycles. One of the most deadly of all known alien species, these creatures need a host organism in order to reproduce.

The typical Xenomorph starts life as an egg-like creature which, when detecting the presence of a potential host, opens up to release the second stage: a small quasi-arachnoid life form which launches itself onto the host's face and impregnates it with an endoparasitoid larva, which later consumes the host from within and exits the body as a vaguely worm-like organism, which then grows very quickly, developing into the adult Xenomorph.

Although numerous varieties exist, the adult Xenomorphs all tend to share some common traits: a vertebrate-like body, a protective exoskeleton, a long flexible tail, an elongated eyeless head, and a toothed maw which hides a retractable inner mouth. Little is known about their biology, but it is known that they eat with their "tongue mouths", not their outer mouths. This mouth is somewhat similar to the pharyngeal jaw of a moray eel. They also bleed extremely acidic fluid which is yellowish green in color and often referred to as "blood", although whether it's used to transport nutrients through the body and/or serves other functions is not clear.

Xenomorphs appear to possess a roughly similar intelligence to that of a typical primate, but have been shown to learn relatively fast and utilize the situation around their environment. It has been suggested that the creatures may have a hive mind, or a collective consciousness directed by the Queen, who can call back and give orders to her warriors, telepathically and with shrieks.

In the rare event that a Xenomorph finds itself under attack or otherwise vulnerable, it might display incredible creativity and cleverness. They are capable of moving quickly and silently in ventilation systems, despite their size, and will use such conduits for ambush, escape, or simply as an easy way to travel between areas.

Xenomorphs are conscious of the effects of their acidic blood, and will use it to their advantage - to break out of confinement, or as a weapon. They show some military tactics (such as retreating when overwhelmed), and can find ways to get around certain problems (such as pushing the red button). They know that the darkness is their ally, and break lights to create cover.

The adult Xenomorph is a living weapon, noted for its ferocity and deadliness in any condition. Once fully matured, they have great physical strength and agility. They are masters of stealth; a favored method of acquiring prey is to wait in a dormant state until an appropriate victim strays near, and then drop down silently from behind or use its tail to impale whoever walks by. The prey is generally blind to the fact that a Xenomorph is present, due to its propensity to camouflage itself within its nest walls or the surrounding artificial environment given its bio-mechanical-like appearance. A Xenomorph will also use its pitch black carapace to its advantage, lurking in the shadows whilst waiting for prey to stray too close.

Adult Xenomorphs are quick and agile, and can clamber along ceilings and walls, a skill they exhibit freely whether they are evading others, attacking, or hunting. They can survive in extreme temperatures, are well-adapted to swimming, can respirate in harsh atmospheres, and can survive in vacuum for short lengths of time. Their movement tends to be silent, and they do not radiate heat as their exoskeletal temperature matches the ambient temperature. They also salivate profusely. This saliva is not acidic, though some Xenomorphs do have the ability to spit acid, which may come from their stomachs, a special gland somewhere in their throats, or acid pouches lining the head. This can be used to blind victims, much like a spitting cobra.

Drones are very much like worker bees or ants. Their main tasks are to keep the hive in good condition and protect it from attackers.

The Queen secretes hormones that keep them sterile, and when she dies, the Drones go into a rage, fighting with each other until they find the strongest among them. Which the winner female is usually already molted into a Preatorian. That Female will then evolve into a Queen and immediately begin to lay eggs. She will also choose whether to keep the Praetorian consorts of her predecessor, or choose a new pair of Warriors for the role.

They average in size at about 6–7 feet tall standing on hind legs, and about 14–15 feet long, tail included. They have the basic body build of the Warrior, except that their dome is completely smooth, where as the Warrior's dome is more ridged. Drones are smaller and somewhat more delicate than the Warriors, not considered quite as dangerous by Yautja standards, but striking fear into the heart of any human.

Like all of their brethren, they have acidic body fluids, but only the Drone can spit this secretion onto prey over a short distance.

Drones have an organ in their body that releases a sticky fluid that they can spit out of their mouth onto any surface. It can be used to harvest hosts for the Queen's Facehuggers

The Scout is a breed of xenomorph built for speed and agility. It specializes in tracking and path finding for resources, as well as a capable harvester. Though comparable to a drone in size, the scout sports a longer tail that may be used to grasp terrain, and shorter dorsal spines to help the scout fit in tight spots, as well as a lack of dorsal fin. This, however, does not slow down the scout in water, as it is actually one of the best swimmers. Like most xenomorphs, it is unknown exactly what causes a scout to be born. Theory suggests these classifications may have to do with the host itself, or incubation periods. Further research is needed.

The larval form of the scout is unique, in that it trades the long slithering body of most larval forms for under developed legs. Scout larva have been spotted outside the hive on occasion, getting a head start on their lives.

Warrior Xenomorphs - commonly known as simply 'Warriors' - are the soldiers and protectors of the hive. They are all children of the hive's Queen, bigger and stronger than the Drones. The Drones are less deadly, and somewhat less intimidating.

Warriors average in size at about 8 feet tall standing on hind legs, and about 14–16 feet long, tail included. In most cases, the Warrior looks the same as a Drone, except that the dome on top of the head is completely gone.

They evolve into Praetorians, which serve as the Queen's consorts. Typically, there are four of them at any given time. However, when the Queen wishes to watch them battle for her attentions or increase protection in preparation for an attack on the hive, she will release pheromones which cause four additional Warriors to evolve into Praetorians.

At this phase, an adult praetorian is capable of laying a small clutch of eggs at a time with an ovipositor, which is smaller than a full queen's. Standing at nearly 8' tall, a praetorian is a heavy and dangerous breed of xenomorph. The smaller set of arms on the front of the chest have developed at this stage to assist in crawling low to the ground, as well as for holding and carrying anything the praetorian may consider important, allowing its primary arms to be freely used. The long tail is equivalent in length to a scout.

roles within the hive are as follows:

Royal Guardian-

Found deep within the hive, usually around the central nest. This is usually true at a phase IV hive, with 2 praetorians. When in this phase, a praetorian does not breed or lay eggs. Instead, she lay dormant until needed, or until she is replaced and can venture from the hive to start her own nest.

Young Queen-

Throughout a phase II hive, a young queen remains in her praetorian stage. Initially, at Phase I, she is very active in all aspects of a xenomorphs life, hunting, breeding, and surviving just as much as her lower caste of followers. When the hive reaches phase II, she tends to stay within the nest during the day, spending a majority of her time breeding and laying eggs. At night, she ventures out of the hive to hunt for stronger hosts, evolving the hive. When the hive is formed beyond its base and frame, the queen enters a state where her primary focus is to mate. A mental key unlocks her followers genetics, forcing a sexual metamorphosis upon her hand picked followers. The aggressive new males will compete to breed. Only the absolute alpha may mate with the praetorian at this stage, as their combined genetics will be responsible for the next generation. This competition can be in many directions. Males with higher intelligence may attempt to make an impression to their young queen through advanced methods, this is common among drones, who are rarely chosen. Warriors take on a more brutal challenge: slaughter their competition. Scouts often leave the hive and travel to extreme distances or dangerous heights to bring back something unique or special. The rate of breeding for a scout is similar to a drone. Though it has never been recorded, it is assumed that a hybrid will be an automatic pick for the young queen, though the competition may still be in play.

Once the alpha is picked, the pair will breed. The male will donate his body to the young queen once he has deposited all of his genetics to her, as this process is fatal. Once the male has passed on, the remains decorate the "throne". It is unknown why these particular remains are used, as they do not seem to reinforce the hive. It has been noted that there is almost a pattern to the parts used. The praetorian will then metamorphosis into a full queen, beginning the third phase of the hive.

The Queen is the largest and most intelligent Xenomorph and can grow incredibly large, up to 100 feet tall if given time, though they average closer to 15 or 20 feet. She lays many eggs that hatch to become the first stage of Xenomorph. It is unclear whether the Queen engages in combat outside of protecting her hive. The Queen is usually nestled deep within the hive, protected by Praetorian guards.

She is the most dangerous of the hive, displaying extreme aggression and using her intelligence to devastating effect.

When attached to her egg sac (ovipositor), she is immobile and vulnerable to attack. When she removes herself from it, however, she can move surprisingly fast. She attacks with her four clawed arms, as well as her long, bladed tail. She has also been shown to use her main and inner jaws in combat.

Queens are created through Royal Facehuggers, which produce Praetorians or immature Queens. When a Queen dies or abandons a hive a Praetorian may fully develop into a new Queen and take its mothers place.

The king only makes himself known when a new queen needs to establish a hive, or when the queen rips herself from her birthing pod, to start off the reproductive cycle. Once the king has mated with the Queen he will leave the hive, for fear of attack from the hive, or even the Queen herself, who will want to protect her eggs from any possible threat. He will search for a place to rest, another queen to mate with, or food until he is needed again.