- "More of what?! What the hell are those things? Is that the crew?!"
- —Kendra Daniels
Necromorphs are mutated and reanimated corpses, reshaped into horrific new forms by a recombinant extraterrestrial infection. The resulting creatures are extremely aggressive and will attack any uninfected organism on sight.
The sole purpose of almost all Necromorphs is to acquire more bodies to convert and spread the infection. They are believed by some to be the heralds of humanity's ascension, but on a more practical level are the extremely dangerous result of exposure to the enigmatic devices known as the Markers.
The Necromorphs are controlled via the Markers by a group of entities known as the Brethren Moons, which are massive Necromorphs created after nearly every living organism on an inhabited planet unlucky enough to come into contact with a Marker has been killed and infected. The Necromorphs's motivations are to create a mass of necrotic flesh to be collected by the Markers during a Convergence Event with the intent to create another Brethren Moon.
- "Holy creatures, transform me into your humble servant. Show me the path to enlightenment as you alter my flesh and free my soul."
- —Samuel Irons
The generation of a Necromorph begins with the Markers. These structures broadcast a highly concentrated electromagnetic signal that alters any dead tissue in range on a cellular level, converting it into pure Necromorph tissue and re-animating the corpse of the host organism. This signal also affects the minds of any nearby intelligent life forms, usually manifesting as dementia and resulting in homicidal/suicidal actions, essentially setting the stage for the coming Necromorph infection.
The infection is also spread directly through the Necromorph pathogen – that is, the reanimated cells created by the Markers and which compose the Necromorphs. Typically, the infection is passed on to new host bodies via specialized Necromorphs such as Infectors or Swarms. In order for the Necromorph pathogen to infect a host body, the host must first be dead; for reasons unknown, living victims who come into contact with the microbes do not undergo transformation, although symptoms of paralysis, catatonia, and impaired breathing can occur. While these symptoms do not necessarily ensure the death of the host, they can make it easier for nearby Necromorphs to catch and kill them. Living victims that ingest Necromorph tissue in large quantities undergo a gradual transformation, eventually dying of starvation and becoming Feeders.
Infection via Necromorph Swarms, witnessed during said creature's death scene, shows that the host immediately turns into a Necromorph; as the screen immediately fades, the host's new form can't be ascertained, but has been speculated to be a Fodder. Swarm-infected hosts retain their appearance prior to being "hijacked".
Once the host is dead, the recombinant properties of the infection take hold. The process is extraordinarily rapid, and predictably violent. Cellular functions go into a self-destructive overdrive, creating new biologically active compounds which are then metabolized by reanimated flesh to fuel further mutations. Bones are broken, put together in new configurations, or reshaped into entirely new forms. All of this takes place within a matter of seconds, and the process generates tremendous amounts of heat. More often than not, the violently spasming corpses become so hot that stagnant blood begins to boil in the veins and arteries, rupturing the skin. Previously Vital and digestive organs that are no longer needed are broken down and turned into additional musculature, giving all Necromorphs increased physical strength.
Pure Necromorph tissue is light pink and translucent; it is capable of independent movement and sticks to surfaces. The pink tissue is capable of consuming and reconstructing necrotic flesh, and can transform living flesh when injected directly into a living person's bloodstream.
The type of Necromorph created during infection largely depends on location and circumstance. For example, Lurkers are usually created from the infant-like organ banks used for medical transplants, human-born infants or in other cases, dogs. Guardians are created from hosts who have been affixed to the Corruption, and Stalkers are believed to be created from human twins. However, some Necromorphs are clearly composed of more than one human (see Brute, Tripod or Graverobber), which is an indication that some form of intelligence is at work allocating biomass for specific use.
In certain cases, Necromorphs have been created via the insertion of Necromorph tissue into the brain of a living host. This results in exceptionally powerful Necromorphs capable of regenerating severed appendages in a matter of seconds. The most well-known Necromorph of this type was the Hunter, an experiment of the crazed Unitologist Dr. Challus Mercer. Other similar Necromorphs include the Ubermorph encountered on Titan Station and the infected members of the S.C.A.F. Deep Dig Team on Tau Volantis.
All Necromorphs are extremely hardy and capable of surviving in lethal environments such as the vacuum of space. This implies a total lack of respiration or reliance upon vascular activity, which explains the Necromorphs' resistance to wounds that would cause massive blood loss due to hemorrhaging in uninfected humans.
Many Necromorphs feature yellow, luminescent tumor-like growths or pustules; these sacs often explode violently when ruptured. It is possible that these organs serve as sources of energy for the Necromorph.The Necromorph infection is not only limited to humans. Dead Space: Martyr describes a Necromorph fish which behaves like all other Necromorphs, as it attacks another fish in order to kill and infect it. Lurkers, although typically created from cloned organ banks and human babies, can also be created from dogs. On the planet Tau Volantis, numerous Necromorphs created from native extraterrestrial species were encountered. Thus, this implies any living organism in the universe can be infected, no matter the species.
- "They're not monsters, they're animals. Deadly animals."
- —Catherine Howell
Necromorphs are highly aggressive; they will attack any non-infected being on sight, regardless of species or age. The sole purpose of this behavior is to kill new hosts and spread the infection as quickly as possible. Despite being viewed as mindless killing machines, the creatures sometimes display tactical planning and cooperative behavior. They commonly hunt in small packs of mixed individuals with semi-specific roles, and use stealth, ambush, or group tactics to outsmart their victims. This requires a degree of strategic thinking, and points to a certain amount of individual intelligence and communication. Examples of this include using ventilation shafts to sneak up on prey, playing dead, not attacking until the victim is well within striking range or their back is turned, or using a lure to draw known threats into an ambush.
Necromorphs share a form of collective intelligence, allowing them to act in a coordinated manner during an outbreak. This shared consciousness was formerly believed to originate from powerful Necromorphs such as the Hive Mind or Nexus; it is now known that all Necromorphs are controlled by the "Brethren" Moons or Brother Moons. It was previously hypothesized that this was exclusive to the Tau Volantis Moon. However, after its destruction and subsequent awakening of the other Brethren Moons, it is shown that active moons are capable of creating and manipulating Necromorphs from incredible distances.
Necromorphs not currently engaging a non-Necromorph target have been observed as performing several different behaviors. Many will wander aimlessly, almost passively, with no real destination, until they are aware of a new victim to kill that they will immediately engage. Some will drag bodies to a different location, possibly to make it easier for an Infector to find as seen on Dead Space 2: Severed. Some will hide themselves inside ventilation shafts, setting up new or resetting previous ambush sites. Some will simply stand in place, waiting for a new victim to come to them. When a target is present but out of range, they will often watch the victim and attempt to intimidate them with loud growls and threatening poses. Feeders are observed to do what appears to be eating when no living beings are nearby.
Beyond pack tactics the creatures have never really been observed to directly interact with one another (other than the Stalkers and the Pack, see below). They do not audibly talk to one another, they do not touch each other in a social sense (though one might get in the way of another during an attack), and they have not been recorded exchanging more subtle chemical signals between each other, i.e. pheromones are never mentioned.
The scope of their behaviors is expanded upon in Dead Space 2 with the introduction of Stalkers. Outside of the Brethren Moons & Hive Minds, Stalkers seem to have the strongest sense of pack cohesion and individual intelligence shown from Necromorphs, as they will often peek around corners to lure Isaac while another will charge from a different direction. They are also the only known Necromorphs to directly communicate with one another. The noises they make seem to hold some significance, e.g. the Stalkers will make a noise while or just after Isaac has moved his location, alerting the other Stalkers. It is also possible that they communicate with each other, such as the Pack.
In Dead Space 3, it can be seen that when Necromorphs are left idle for years at a time, they curl up in a hanging patch of the Corruption to conserve their energy and wait for unsuspecting prey. This results in the Necromorphs becoming mummified and fungus-like in the process if left in this state. An example of this is seen when Isaac and Carver enter the dilapidated CMS Roanoke, a 200-year old ship in orbit over Tau Volantis. A form of Necromorphs called Fodders are seen carrying melee weapons, something that is odd for Necromorph behavior as they never wielded man-made tools before. This could mean that some Necromorphs are evolving and may have gained a slight form of intelligence or quite simply, their behavior might be actualized contextually by the common consciousness. Another example of Necromorphs using contextual adaptation as a form of intelligence are the Creeper and Shambler. When the Creepers take over the body of a S.C.A.F. or Circle soldier's corpse, they immediately know how to use their gun functions and will wield the weapon, albeit in a rudimentary manner with poor accuracy (indicating a low level of fine motor control). One other theory as to why Necromorphs can carry weapons suggests that when the hosts died, their hands froze due to rigor mortis, still holding onto their weapons. But this may not be completely true, because in the prologue of Dead Space 3, the first Fodder encountered released its weapon into the man's back and picked it up after he had fallen.It is also possible that Necromorphs are simply "puppets", being truly dead bodies and having no form of metabolism and behavioral reactions whatsoever, but being instead just what one calls "eyes, arms and legs" of the Brethren Moons, as the Unitologist Cult repeatedly chant, implying that Necromorphed beings may not be "living" at all.
Dismemberment and Incineration 
- "Take their legs out, and they'll drag themselves toward you. Shoot off an arm, and they'll use their other arm to rip into you. Nope, the only real way to take these creatures out is to completely rip them apart."
- —Glen Schofield, Dead Space Executive Producer
The Necromorphs had specific vulnerabilities depending on their archetype. Wounds that may "kill" certain Necromorphs may not necessarily kill human beings and vice versa. Despite their apparent similarities, one should not assume that the vital organs of either forms are similar. For example, most human beings can survive having all of their arms and legs amputated cleanly while most Necromorphs can survive having (all of) their heads amputated cleanly with the reverse being fatal in almost all cases. However, both organisms as it is with all known organic systems seemed to assume a state of lifelessness after a sufficient volume of blood loss is induced. When dealing with a Necromorph, it is advisable to induce as much blood loss as possible by any means necessary while shooting at the torso or head are inefficient ways to deprive a Necromorphic host body of blood. Enough shots to the head or body will eventually drain the body to the point where it assumed lifelessness i.e. the physical inability to mobilize themselves despite the presence of any functional limbs still connected to the host. The typical Necromorphic limb had for all practical significance, similar characteristics to a shaped mass of spongy muscular tissue made hard via engorgement with the host's blood. It is commonly observed that removal of such limbs will cause the host to lose a substantial amount of blood while the limb itself turns flaccid.
The second method to dispose of a Necromorph is incineration. Most Necromorphs will be killed if they sustain heavy burns.
Countless combatants died due to not knowing a specific Necromorphs' specific vulnerability via dismemberment. One systematic approach to "killing" these creatures is to chop them to pieces by removing their heads, arms, legs and other extremities until the body assumed lifelessness. Some Necromorphs such as The Hunter, The Ubermorph and The Hunters (Tau Volantis) are ineffectively neutralized by dismemberment alone as they are able to regenerate their limbs quickly. One way to permanently kill these Necromorphs is by destroying the entire creature at once as it is seen when Isaac killed the Hunter by burning it with a shuttle's engines.
The act of strategically removing the limbs from the creatures is dubbed "Strategic Dismemberment" by the Dead Space game team. Each creature had their own strategies when it came to dismemberment and to know them is indispensable in a game where the supply of ammo is low by definition: Some creatures will simply die after enough limbs are removed. Some creatures will die instantly if a specific limb is cut off while some creatures will become even more of a threat if shot in the wrong place. Learning how to dismember creatures is mostly done through trial and error. However, dismemberment is the only effective way to truly stop the reanimated horrors in their tracks and is the best way to survive. In Dead Space 3, dismemberment did not play as big of a role in killing the Necromorphs. If a weapon did a large enough amount of damage per hit, a damage upgraded Seeker Rifle for example, it can kill them with a single hit in the chest or one of the limbs even on the hardest of difficulties. The Feeders are also the only Necromorphs whose weak point is the head. With every other variant, shooting the head will only drive it into a berserker like rage causing it to swing their arms wildly and keep walking toward their prey.
As of Dead Space 3, the various types of transformations that certain Necromorphs took on after specific limbs are cut off made it hard to safely know which limb to dismember and which one not. The most surefire way of subduing these creatures is to remove an arm and a leg as this will prevent almost any kind of further transformation of the torso and legs. This method is highly advisable on Wasters, Slashers and Pukers as they died instantly when this is done. Wasters will also not be able to mutate.
- Necromorphs share similarities to a number of other creatures featured in science fiction films, literature and video games:
- Necromorphs are similar to the "Xenomorphs" in the Alien movies in that they will travel by vent or other areas that they climb from for the element of surprise. Both species also parasitize human bodies in order to reproduce. Both are named after two of these and the last word, "morph".
- Necromorphs are similar to the Flood from the Halo series and The Many from System Shock 2. All three infect other lifeforms, twisting them into undead creatures designed to infect more hosts, and are controlled by gargantuan creatures composed of countless corpses.
- Necromorphs also bear a resemblance to the monsters from the 1989 movie Leviathan. In the film, a deep-ocean mining team encounters a mutagen that can merge, re-shape and reanimate the corpses of the dead. The plot of the film bears some parallels with that of Dead Space: Martyr.
- Necromorphs also share similarities to the alien species referred to as 'The Race' featured in the 2002 game Run Like Hell in which they are both creatures that require human corpses to create new creatures or to modify existing beings. As well as both species being able to communicate to the human protagonist through crude methods (Brethren Moons using the Markers and telepathic means, whilst the race turns humans into creatures that share their characteristics as well as personality and intelligence). Interestingly both species also use corpses to create flesh-like walls that slowly consume the environment around them.
- Necromorphs also have traits resembling the parasitic alien life forms from The Thing franchise, specifically the John Carpenter film and its prequel. The Thing is an alien life-form that infects and assimilates its victims into a perfect imitation of the former human and can replicate their traits, but is also able to mold their body into new forms that allow it to fight, such as a set of teeth in the rib cage and large tentacles.
- This parallel is taken further in Dead Space 3, where the primary setting is on a frozen planet, and the setting of both Thing films was in the antarctic.
- The early ideas for the Necromorphs was that they were some sort of bloated, translucent corpses that had floated ashore on a beach. However, this concept was put aside and later changed to as how they look now. Apparently the creative team of Dead Space created hundreds of concept for the looks of the Necromorphs.
- As seen below in the gallery, the developers seemed to first go for an insect-like look of the Necromorphs after scrapping the bloated corpse-look, that later changed into more human-like. However, they kept some insect characteristics for the Necromorphs for the final productions.
- Not once in the series does any character, playable or otherwise, say the name of any Necromorph, save for the Leviathan, the Hive Mind and the Nexus. The Tau Volantis Moon is not referred to by its full name and is only mentioned as a moon. A plausible explanation to this is that the characters in the series has never come up with names for these creatures, as naming them seemed almost pointless except for the purpose of identifying each individual strain, which is not particularly helpful during a large-scale outbreak.
- As a side note, Necromorphs of any kind seemed to completely lack their former human genitals, despite most Necromorph forms being naked. These extremities have likely atrophied or somehow "converted" into more useful biomass during the human's transformation, or that it is just pointless for Necromorphs to have them. Another plausible explanation is that the developers have censored them on purpose.
- Despite the term "Necromorph" being coined by Dr. Terrence Kyne in 2508, Earl Serrano somehow knew of and used it many times in his logs in 2314, almost 200 years before Kyne first invented it. This is more than likely an oversight by the creators.
- The term "Necromorph" is a neologism comprised of the root words "necro" (from the Greek word νεκρός, nekrós) meaning "dead" and "morph" (from the Greek μορφή, morphḗ) meaning "form" or "shape"; thus "Necromorph" can be translated into the synonymical morphologically parsed term "Dead-Form", an apt name for the creatures given their nature.
- According to the design team, the key idea of the Necromorphs is that they are made up entirely of human body parts: scythe arms were once the bones of the human host, tentacles are made up of a host's intestines, etc. The result is that the entirety of the Necromorph is comprised of re-purposed organic parts from a previous host or hosts. The team studied medical, autopsy, and accident photos in order to recreate the effect of a ravaged human body, to give a sense of realism as to how the human bodies in the games have been twisted into monsters.
- The Necromorphs seem to be less inclined to attack those under the influence of the Markers, as shown in the comics. Natalia Deshyanov was not attacked by the Necromorphs as she was making her way to the rover bay, only observed. This could also be said for Dr. Mercer and Nolan Stross, and how they were able to avoid infection. They more than likely don't attack due to the fact that although they are not Infected, they are still being controlled/influenced by a Marker.
- As seen in Dead Space 2’s multiplayer, Necromorphs can see neuron strands in the human body. It is possible to speculate that Necromorphs can sense electric impulses (neurokinetic impulses). This would explain why the Pukers, having had their sensory organs melted off, are able to accurately determine the location of the player and aim their acidic spit at them.
- If a Necromorph places Isaac Clarke, Gabe Weller, or John Carver in a quick-time event with other Necromorphs around, the other Necromorphs will just wait patiently to attack while Isaac, John, or Gabe fight off the holding Necromorph. This does not include player controlled Necromorphs or AI Slashers in the Multiplayer section of Dead Space 2.
- In Dead Space 3, the first Necromorphs encountered on the Roanoke 200 years after the outbreak that wiped out the flotilla and the expedition, are lying dormant on the ceiling attached to small corruption pods. This suggests that when a planet, colony or ship is totally overrun but without triggering a Convergence event, Necromorphs roam freely without any non-infected target to attack and simply do nothing to do until they "fell asleep" and make a pod out of corruption (or the pod comes from their own flesh when placed on a surface for a long time) and begin to hibernate indefinitely. In such state and with the extraordinary condition they posses, they can last for centuries, maybe millennia in a perfect condition; although the skin of the host (at least the first layers) seems to fossilize and became dry and skeletal. Despite this, they hold the same strength and power as their freshly-made-cousins on the Ishimura and the Sprawl.
- When lying dormant, Necromorphs are still aware as they can awake when a non-infected life-form is close to them, as it happens to Isaac when he finds the first ones on the Roanoke. This implies the awakened Necromorph can telepathically signal the rest of its brethren to hunt Isaac and Robert Norton's crews, which explains why the rest of Necromorphs on the other ships and the surface of Tau Volantis are already active when players make it there.
- Similarly to the previous statement, Necromorphs on the same flotilla will bleed when a limb is shot off which is odd because these Necromorphs are skeletal and have dry muscle. In reality, bodies in this state no longer contain any bodily fluids. This is more than likely an oversight by the developers.
- Although it could be that in such condition, the Necromorph is well preserved within the mummified body of his former host. Hence why they bleed when shot and dismembered.
- There has been a glitch in Dead Space and Dead Space 2, more visible in the second game, when after the animated Necromorph scene has finished, the Necromorph that killed the player will freeze and other nearby Necromorphs can attack and desecrate Isaac Clarke's corpse further than the death scene already has. This happens because the screen takes too long to run red with blood. This glitch has been fixed in Dead Space 3.
- Despite being seen using new models in Dead Space 3, the Enhanced versions of most Necromorphs encountered in game still use the Dead Space 2 models (i.e. Slasher, Leaper, Puker, etc.).
- Most Necromorph variants have static facial expressions, especially all Slasher variants. This is because it would take time to animate them, and it also creates the uncanny valley effect to make them more horrific.
- The Brethren Moons never even mention Necromorphs. It is highly likely that they see them as men tools to create new brothers.