A Xenomorph is an alien life form that uses a host to breed.
There are many stages in a xenomorph's life cycle. The first stage is the egg, which is a dark shade of green and is leathery. When there is movement near the egg it opens up and releases a facehugger. The facehugger only lives for a short amount of time. It finds a foe, and clings onto it over the mouth. It then shoots a tube down the host's throat, and implants the alien embryo. The facehugger then dies and falls off the host. A few hours later, the developed alien will burst out of the host chest in the form of a chestburster. The chestburster will shed many times and develop into an adult alien which is a dangerous threat to all nearby life. Some aliens will develop into queen aliens, which lay the eggs, thus restarting the life cycle.
The Xenomorph has no eyes, yet is well suited at using it's other senses to navigate and hunt. The Xenomorph is equipped with a bladed tail with can be used as a deadly weapon. When injured, the alien will bleed green, acidic blood, which is capable of melting through flesh, metal, etc. The xenomorph has sharp claws and fangs, and is extremely stealthy, using surprise attacks at some times. In the xenomorph's mouth is a second mouth which is extendable.
After a chestburster erupts from a host's chest, it will show traits of the host's form. This means the xenomorph may take DNA from it's host to be more adapted to its' surroundings.
Facehuggers come out of an egg that the xenomorph Queen laid. They find a host to lay an embryo in.
Hatches from the egg laid by a facehugger. Grows into an adult xenomorph.
Fully grown chestburster. Have at times showed high problem solving techniques, have shown to be aware of their blood's acidic properties.
A Queen is basically a queen of a hive, Xenomorphs are like ants, they have many different jobs like a warrior or a drone. On the other hand a Queen Xenomorph is one of the only xenomorphs that can reproduce/Lay eggs and is extremely large. A Queen xenomorph can only be created by a Royal Facehugger which even then creates a Predatorian Xenomorph which can only be made a queen once the past queen has died.
A chestburster that came out of a dog, it contains traits of the dog and once fully grown, is fully quadrupedal.
A chestburster that grew inside of a Predator. Has mandable-like features on its' "face".
The result of a facehugger that went on a Predator's face that lays a embryo inside that hatches to the chestburster after the chestburster shed it's skin the adult predalien comes out it's the size of a Praetorian and has the strength of a predator. In the beginning of AvP Requiem they show a chestburster come out of a Predator.
A hybrid of Xenomorph and Human. Appeared in Alien: Resurrection.
Perhaps the true origin of the Xenomorph, a race called the Engineers created a black liquid substance as a biological weapon. Breaks down the Engineer's cells, and mutated the DNA. Despite this, it only mutated the human's DNA. Appeared in the movie Prometheus.
When an alien/human fetus was removed from the womb surgically, the squid-like creature soon grew unobserved, into a large version of a facehugger. It planted itself into an Engineer.
May be either the very first, or the most evolved version of the Xenomorph. Most likely the former. Does not have a chestburster form. Erupted from chest of an Engineer. Appears in Prometheus.