Sub-species: Beasts of Prometheus and Resurrection

There are a number of creatures which seem to have spawned from the same DNA of the Xenomorph but would not be classed as one.

Hammerpede 
This creature first appeared in Prometheus and seemed to be some kind of larva worm that was exposed to the fluid from the ample chamber of the Jockey ship. Very like an earth cobra this little beast was aggressive and savage like a xeno. It shared the trait of acid blood like the xenomorph but also had the ability to regenerate itself from damage or attack regrowing its head after Fiefield cut it off.

The Decon

While man people call this a jockey xeno or a proto xeno however this creature didnt spawn from a facehugger but a human born creature that mutated in a massive facehugger like beast. The creature emerges fully formed from the jockey and cuts it way out with is crown blade very unlike an infant xeno. The jaws while like a xeno are more like a goblin shark which inner jaw expands the full range of the mouth. Also it has a placenta when its born which a xeno does not.

New Born

More of a gene splice gone wrong. When Ripley and the Queen DNA get mixed in the cloneing process and now the Queen has a human womb and gives birth to this monster. A loathsome creature with human eyes and features. This beast is like a toddler which dosent know its own power and with a creepy wide eyed wonder of a child this beast is the one of the few things in an otherwise letdown of a movie.

Xenomorph caste 5:Drone

Also known as the Lurker the Drone was first encountered buy the crew of the Nostromo. The star beast is somewhat smarter then the warrior xenomorphs....as it was alive a shorter time period on the ship then the Warriors on LV426 yet still managed to evade capture and death at the hands of the crew. The Drone also seemed to be some what taller hence its other nickname "the Big Chap". With bigger dorsal horns and blade its a sight to be seen.
One other feature that the Nostromo Drone had that the Drones who later appeared in the series lost was the transparent skull. The dome was see through and underneath was a human skull making it even more frighting and savage something I think was lost with the later versions.
However it seem this design is returning with Alien Isolation and with it all the terror of being hunted buy a Lone Xenomorph. Its only fitting too as this was the creature that started it all.

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Xenomorph caste 4: Warrior

While not as sleek as the Drone and not as agile as the Runner the Warrior xeno is still the more deadlier of the Xenomorph castes. This species is found in large hives close to the queen. Their exoskeleton is ridged and bulky while not making them totally bullet proof it does make them hard enough to kill. Their armor also hides them among the hives organic walls.

While not as clever as the Drones they do seem crafty and mainly take orders from the Queen. While not having any outstanding features from the other xenomorph's the warrior is still a savage creature.

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Xenomorph caste 3: Runner

While not a much loved Alien movie Alien3 for me is still pretty awesome and one of the elements which made it so was the introduction of the Runner xenomorph (The term Dog Alien was dropped buy many fans with the revelation of the alternate cut). Alien3 showed us that the xeno would take on elements of what ever creature it facehugged. In Alien3 a Dog/Ox depending on which cut you watched.
As a result the beast chose a quadrupedal stance over two legs as its legs were longer then a human spawned xeno. It also lack dorsal horns and seemed to prefer to kill the convicts on sight( although this could have been it protecting the unborn queen Ripley was carrying) One could also speculate that because of a more basic host it do's not have the smarts to harvest the convicts for the maturing queen.

The beast could reach powerful levels of speed equal to a jungle cat be it walking on any surface. The "Dragon" as Golic called it has the highest kill count of one single Alien in any of the movies.

The creature would turn up in a number of games and be one of the more unique foes with its speed and agility.

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Xenomorph caste 2: Predalien

The Predalien is a savage bi-product Yaujita born xenomorph. First feature in AVP war it was more sturdy and robust then your standard xenomorph killing a detachment of marines swiftly and with ease. The Predator race considers the beast a violation of their religion and must be killed on sight.
While the more obvious traits of the predalien are its dredds and jowls of the predator its also has taken it's strength.

In AVP:R one got loose in Gunnison Colorado and started a hive via impregnation of female humans...be this because it was a Predalien or because it was a Praetorian is still unknown. When combating a Predalien Marines are advised to use a Smartgun or a Sadar. When a Predator fights the creature it uses a Smartdisc or Combistick. What ever weapon one choose's their is no doubt the Predalien is a savage and frightening foe.

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Xenomorph caste 1:praetorian

While never featured in the movies this is one caste that has appeared a number of times in the comic and video game part of  the universe. Described as the Queen's royal guard Praetorians are smaller then queen but bigger then a warrior or drone. Their crown is like the Queens but their body is more like a warrior with the dorsal horns and back blade. They are savage in their attack and while they lack the ability to crawl on walls they make up for it in speed and in endurance. When combating a Praetorian in any a fight heavy weapons are suggested. If your a marine and have a M41A Pulse Rifle use the gernade launcher or if your a Predator use the spear or a fully charged Plasma Caster blast. Another idea about the Praetorian's is that they are juvanile queens and once their charge is dead the two guards must fight to the death and remaining beast will molt into the Queen.
Some have also suggested that the Predalien in AVP:R was a Praetorian with her odd shaped crown and giving she was able to implant chestbursters into host's although this might have just been an ability solely belonging to a Predalien.
Given the savage nature and unique design it would be cool to see such a beast in one of the future films.

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