The Lurker is a Xenomorph caste that shares very similar qualities to the Alien. Lurkers are easily identified by their usually smooth head carapaces. Unlike the far more common Soldier caste which tend to employ direct assaults and swarm attacks, using sheer weight of numbers to overwhelm defences and subdue their prey, Lurkers prefer to keep their distance and lurk in the shadows, only attacking when the time is right.
Lurkers tend to walk on all fours most of the time, although they have been known to stand on two legs when fleeing or attacking with their claws. Lurkers are dark in color, typically black but can switch to one of five new tones (Aureus, Inquinans, Caeruleus, Aeruginosus, Porhyreus). Their most distinguishing features are their smooth dome heads. Some Lurkers also have what resembles a human skull underneath their domes, similar to the Alien. Lurkers also have thinner dorsal tubes than most Xenomorph castes, three fingers, green tinted shoulders and feet identical to that of a Soldier. Lurkers use their agility to outsmart prey. This form of attack requires a thin, spindly figure, which makes it trade brute force for overwhelming speed. Lurkers also have a stronger exoskeleton than Warriors giving them the ability to take more damage.
The Lurker Xenomorph is regarded by some as the perfect hybrid between a Soldier and a Runner. It almost has the same speed and prowess as a Runner does, mixed with the strength of a Soldier, which allows it to easily knock down Marine opponents.
When attacking, Lurkers primarily employ ambush tactics, and are almost never seen working in coordination with other Xenomorphs, preferring instead to operate alone. They are shown to be intelligent and patient, employing stealth in their assaults, often seeking to blend in with their environment and waiting for their prey to come within range before striking. The Lurker's primary attack is to pounce on their prey and attempt to stab them with their tail or attack them with their claws. Lurkers are also able to leap great distances. Lurkers have been known to create holes in the walls of a Hive next to a Chestburster host. Lurkers will then hide in the hole and blend in with the rest of the Hive and when a enemy gets to close to them the Lurker will emerge from the wall and attack. Lurkers seem to be more intelligent than the Soldier caste as they have been shown commanding them.
- Despite their virtually identical appearance to the Alien, the official strategy guide makes it clear they are a separate caste.