Necromorphs (Dead Space)

The Necromorphs are the horribly mutated, reanimated corpses of the dead, and they serve as the antagonists of Dead Space. These creatures are extremely aggressive, and will attempt to kill any non-Necromorph creature on sight. The sole purpose of almost all Necromorphs is to create more bodies to infect and spread the infection, while the role of one particular creature, the Infector, is to infect corpses to make more Necromorphs.

Origins
The DNA patterns covering the surface of the Black and Red Markers are the codes for the Necromorph infection as noted in the logs as a "recombinant life form". According to data logs, the first known Necromorph infection was during the reverse engineering project of the Black Marker subsequently creating the Red Marker, which occurred on Aegis VII hundreds of years ago by the original Aegis VII doctors. They had set up the lab on a deserted planet so they could test the Marker and its effects well away from any outposts of human civilization. The Aegis VII doctors copied and recreated the life form using the DNA patterns listed on the Markers, resulting in the creation of the lifeform. Initially the "recombinant lifeform" existed only in a petri-dish and remained dormant (what exactly the lifeform resembled is unknown). The lifeform did not react to any of the doctor's tests, and was about to be deemed a failure. However, one day, a doctor did not fully decontaminate himself when entering the lab and a few dead skin cells fell into the Petri dish. As such, the infection by the recombinant lifeform immediately activated and reanimated the dead skin cells.

The Red Marker actually inhibited the necrotic flesh testing and it was then that the scientists noticed that it produced an apparent "dead space" field, inhibiting the Necromorph infection from spreading.

Soon afterwards, an accident similar to the Petri dish incident resulted in the infection of two doctors. They were promptly quarantined, where they soon died and shortly after infection, the two doctors transformed into the very first Necromorphs (one doctor became a Leaper, the other an Infector). When the Leaper pierced a ventilation shaft it promptly began to kill the other doctors, which the Infector then began transforming. This caused the outbreak to commence.

While it is known that all of the doctors on Aegis 7 were killed, very little is detailed on what events transpired after the creatures escaped. A log reveals that, after the initial catastrophe began on Aegis 7, one of the doctors has a "vision" where he has the idea of constructing a pedestal to broaden the signal the Marker is emanating, thereby containing the Necromorph Hive Mind and all infection present on the planet. Since the Marker is found hundreds of years later on its pedestal on the barren surface of the planet, it is suggested that they were successful.

There are four unique Necromorphs, the Leviathan, the Slug, the Urchin, and the Spider all of which are large and grotesque blobs of flesh that utilize their tentacles to attack. How they are created and from what is unknown, but they may be independent organisms or an extreme offshoot of the Brute Necromorph (i.e made from combining several different corpses).

Role in Dead Space
The Necromorphs, as mentioned above, are the main antagonists of the Dead Space series, and are extremely difficult to kill. Considering this, they do not take body shots. These are ineffective and only nudge the Necromorph to jump back, stunned, then continuing to attack. The Creature can only be killed by "Disembering" the creature, meaning all it's limbs must be Detroyed for it to die. As this, the main Character of the game, Isaac Clarke, must fight this horde of Necromorphs that have infested the Colony on Aegis 7 and the Planet Cracker Ship (The setting of the game) USG Ishimura. They are first named in-game in an audio log by a "Doctor Challus Mercer", who said one member of the medical staff called "Doctor Kyne" had named them Necromorphs. The name was used by Kyne when Isaac met him face-to-face, who revealed that the Necromorphs were controlled by one large Necromorph on the Aegis 7 Planet called the Hive Mind. It seems that the Necromorphs were controlled by this Hive Mind, but when Isaac killed the Hive Mind it was shown that the creatures could survive without their master. This will be proved in Dead Space 2 and also shown at the end of Dead Space (However, it could have been an Hallucination)