The Xenomorphs are vicious predatory creatures with no higher goals than the propagation of their species and the destruction of any life that could pose a threat to them. Like wasps or bees, Xenomorphs are eusocial, with a fertile Queen breeding a host of subordinate castes. The creatures are known for their potent acidic blood and their phantasm jaws, although their biological life cycle, in which their offspring are implanted inside living hosts before erupting violently from their chests, is in many ways their signature aspect.

The Yautja revere the creatures as incredibly dangerous and thus highly worthy prey, notably employing them in initiation Hunts that serve to test young members of their society and mark their progression into adulthood.
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Xenomorphs are primarily solitary ambush predators, although they have been known to adopt swarm tactics when acting in larger groups. Despite their voracious ability to kill, they often seek to take their victims alive to be hosts for more Xenomorphs; victims are taken to the Hive (or simply a secluded location if no Hive exists), cocooned and/or immobilized before being impregnated with a Xenomorph embryo. However, when their target becomes a threat or is deemed unsuitable for harvest, the Xenomorph will not hesitate to quickly dispatch the chosen host.

×××××××The Caste System××××××
Drones: They're the workers. The drones stay within and work around the hive; doing maintenance, expanding the hive, or repair a hive after an attack. When the hive is under attack, they will primarily defend the inside, killing intruders getting in. Drones rarely leave the hive. They're the standard Xenomorph, standing at 7+ feet tall, stretching to 14 to 15+ feet long and have smooth, long dome heads.
 

       - Lurkers: They're a strain from Colonial Marines. They are kinda like another variant to Drones and is similar in appearance to the creatures from Alien: Isolation and the original Alien movie. Difference between Drones and Lurkers, Lurkers prefer to keep distance and stalk targets from within the shawdows, attacking when the time is right. Their size is similar to the Drones, standing at 7+ feet tall and stretching b 14 to 15+ feet long.

Warriors: The hives' soldiers. They're bred for combat, meant to deal with any threats to the hive, with some individuals sent out to guard the hives exterior and protect any outside Drones that are expanding their next, and killing surrounding life that could be a threat. Their appearance varies from Strains 1,2, and 3 but they all stand at 8+ feet tall and stretch to 16 to 18+ feet long with ridged heads.
         - Spitter/Ranger: Another strain from Colonial Marines, variant of Warrior. A Spitters role is akin to that of a gatling gun or sentry turret in that it is a defensive type of Xenomorph that assists its brethren by attacking from a distance through spitting large quantities of acid from their mouths towards their target. Even thoight the other caste can do it, these Xenomorph specializes in this.

Runners/Scouts: These Xenos are spawned from quadrupedal host creatures, such as Dogs. Their role is like Dogs to us, being used to scout ahead for things such as area checks, potential dangers, ect. They're a bit smaller than typical human-spawned Xenomorph, standing at 6+ feet tall and stretching 12 to 13+ feet long with a brownish coloration and the lack of dorsal tubes with a smooth, domed head like Drones. Scouts move around quadrupedally but could move bipedally if they want. Scouts are incredibly fast and agile due to their build.
             -Sentry/Defender: This is the next strain of Scouts. Scouts can evolve into Sentries when the hive has been well established and has found a steady supply of hosts. Sentries are a Warrior strain of Scouts just like Warriors are an evolved strain of Drones. They maintain their speed and dexterity and develop specialized hands and feet adept to gripping, scaling, and climbing, more so than other XXenomorphs. Sentries is the defensive to the Drone offensive as the Sentried role is to protect their weaker siblings alongside the Warriors, such as the Drone or Scout, and protect the hive amongst their brethren as well. In terms of appearance, they have the dorsal tubes and ridged heads like the Warrior

Praetorians: They are one of the final stages that a Xenomorph can evolve to in their life cycle. They are created when a hive population gets over 300 individuals, and acts as both a Royal Guard to the Queen and as army commanders. Unlike other Xenomorph types, Praetorians rarely operate outside of the hive grounds, and are among the largest and most powerful Xenomorph strains, standing at 10+ feet tall and stretching to 18 to 20+ feet long. Visually, they bare resemblance to that of a Queen, possessing a large, decorative head crest smaller in size and the lack of extra arms. Like their sizes, Praetorians are incredibly strong and their thick carapace is known to be bulletproof in some cases, shrugging off damage that can be terminal to their other Xenomorph castes.

The Queen: The Queen is one of the large forms of the Xenomorph that serves as the mother and leader of a Hive. Queens are the largest, strongest, and most intelligent of the Xenomorph castes, and their appearance differs from that of the smaller variants, with a pair of extra arms growing from their chest and a large head crest extending rearwards from their skull. Not much is known about the Queen or what she looks like since nobody has actually seen her.