The Xenomorphs or better known as Aliens are an extraterrestrial, endoparasitoid species with multiple life cycles, possibly originating from the planet known as Lotos Prime. One of the deadliest of all known species, these creatures need a host organism in order to reproduce. The appearance of a Xenomorph varies depending on its host. The human phenotype is generally around 7–8 feet, and roughly 136.0 to 181.4 kilograms in weight, with a long, muscular tail and large, curved, oblong head. The Queen of this species is generally twice as large (they can grow even larger, some even up to 100 feet tall, and stronger if given time) and possesses superior speed, strength and intelligence.
There are no solid facts as to the origins of the Xenomorph species; instead, there are many assumptions which cannot be confirmed. Based on the limited information we have, the most commonly accepted hypothesis is that they are an artificially created species, although another hypothesis says that they evolved naturally on a planet much different than our own. Another theory is the Deacon from Prometheus evolved into the first primitive Xenomorph, though there is evidence stating that this is false.
It was later revealed by biology teacher Hugo Slawter that the origin of Xenomorphs was created due to a supposed biological warfare device (not the kamidogu) created by the Elder Gods. But the atheist chemistry teacher Reginald Watts said that the pre-Xenomorph lifeforms were encountered by an Engineer and the creatures attacked him, and put seeds in him much like a facehugger; thus, creating the first Xenomorph chestburster following the known cycle of life.
Another theory suggests the Xenomorphs could be the result of genetic manipulation by Saurians, as a terminating mechanism about ten million years ago, but apparently it went horribly wrong. As a result, over the years, the Xenomorphs have become an entirely new species in the galaxy. Their terminating substance mutated harmless organisms into somewhat hostile creatures. When humans are "infected" with this substance mate with one another, it produced a different subspecies of "octo-face-huggers" that can grow incredibly large. As shown on the Wiki, this new subspecies, regardless of who it infected, would result in the "Deacon" or "Proto-alien".
Another theory, commonly accepted, touched on in the expanded universe, is they were the alpha-predator of their own ecosystem on a nightmarish and harsh planet (some assume it to be Lotos Prime, but there is no solid evidence). Without their native ecosystem to keep them in check, they have since infested their own kind, and developed into a separate dominate species. Other parts of the universe began to take notice in this interesting species and began them. The Yautja, Humans, and an unspecified highly technological humanoid species introduced began using them as means of sport, terminating mechanism, biological weapons, food delicacies, and scientific experiments.
Xenomorphs also appear to possess a roughly similar intelligence to that of a typical primate, but have shown to learn relatively quickly, utilising the situation around their environment. Although they do not demonstrate human-level intelligence as a species introspection and technological advancement, their queen appears to possess considerable acumen in its social behaviour and manipulation of human technology, such as cutting the power of the LV-426 colony and operating an elevator.
- The Tarkatan Alien is a strain spawned with the Tarkata of Mortal Kombat. It is featured in Mortal Kombat X.
- Within its franchise, the Xenomorphs have been referred to as the "Eighth Passengers".
- A small Xenomorph appears as a dog-equivalent in Area 51 and is shown to urinate acid.
- Xenomorphs have also been featured or mentioned on the planet Duro, and while their canonical status is highly debated, this information implies that the species at some point managed to travel to, and colonise, at least one planet in the galaxy we know as Multiverse Federation.
- Sometimes, the Xenomorphs seem to shake their head slightly before attacking their prey.