|Governing body||Asuran Council|
|Key episodes||"Progeny" (first appearance)|
The Asurans are a fictional race in the science fiction series Stargate Atlantis that bear many similarities to the Replicators of Stargate SG-1. These similarities have led the Asurans to most often be called simply "Replicators" by other characters on the show even though the two life forms are technically distinct.
Desperate for more effective means of defeating the Wraith, the Ancients created the predecessors to the Asurans as part of an experiment to create an artificial bioweapon in the form of nanites that would infiltrate and destroy the Wraith from within. To that end, these self-replicating nanites were programmed with an aggression surpassing that of the Wraith. As they grew in numbers, the nanites began to assume the form of their creators. Unable to remove the aggression that had been programmed into them, giving them a rage they could not contain or understand, the Asurans, as they came to call themselves, requested the Ancients remove their innately aggressive behavior; a request which was denied since their creators sought to use them as weapons and since the Asurans' programming prevented them from doing harm to their creators.
Upon concluding their research into the feasibility of nanites as weapons, the Ancients destroyed their creations and deleted all traces of them from their database, except for the planet's gate address. A few Asurans, however, survived. Through their replicative abilities, they brought about a "second birth" - this time, not only taking the form of their creators, but also recreating their city on a far grander scale.
Its been recently revealed by the Wraith that sometime after their defeat of the Ancients, the Asurans began attacking the Wraith. The Wraith found this foe to be unnatural and distasteful due to their robotic origins. After quickly learning what their enemy was, the Wraith used a computer virus to deactivate a protocol within the Asurans that forced them to attack the Wraith. They, however, did not press their attack against the Asurans and left the machine race to live in their territory where they were completely isolated from the rest of the galaxy. 
Contact from Atlantis
The first hints of the Asurans were seen in a lab on Atlantis where the Atlantis Expedition encountered a sinister nanite weapon that infected the humans in the lab's vicinity. The nanites would kill those infected by them, who would begin to see terrifying images of a death-like figure approaching them before they died. The nanites were vulnerable to an EM pulse. They did not affect those with the Ancient gene (see Hot Zone).
Two years later, the Asurans themselves were discovered by the Atlantis expedition. Their population had grown to number in the millions and some, such as Niam, had even began to contemplate ascension. Already they have a plan to destroy the Wraith, though it is a slow, long term plan that does not have the humans' best interests in mind. Believing that the aggressive tendencies the Ancients had programmed into them was what was preventing them from ascending, Niam enlisted Rodney McKay's help to remove these tendencies. Although McKay's attempts were successful, they were discovered before the rewritten command codes could be distributed to the others.
Concurrently, at the direction of their leader Oberoth, the Asuran city ship jumped into hyperspace in an attempt to destroy Atlantis. This attempt was thwarted by McKay, with the assistance of Niam, who used the city-ship's ZPMs to destroy it. Niam's betrayal resulted in him along with the other Asurans that sought Ascension being reset or purged from the Replicator Collective though some managed to remain. 
Later, it was revealed that the Asurans had, perhaps due to McKay's early efforts, managed to rewrite the part of their initial programming that prevented them from attacking the Ancients. This allowed the Asurans to capture Atlantis, by surprise, and kill the Ancients, who had regained control of Atlantis from Earth, and were now defendeding it. The Asurans secured the city but faced a delay when a puddle jumper that carried a strike force from the Atlantis expedition who, after defying their leaders' orders, left a bomb in the control tower before leaving. The control room faced heavy damage, however, the Asurans began immediate repairing procedures which took up to several hours. They were also probing the minds of General Jack O'Neill and Richard Woolsey for vital information. The damage dealt to them required the Asuran strike team to dismantle their own warship and use it to repair the damaged parts of the city. Using their own ZPM power modules, the Asurans planned to leave the Lantean system and destroy the Daedalus, which was attempting to destroy the city in order to prevent it from falling into Asuran hands. This Asuran strike force was destroyed when replicator disruptor technology was tied into the shield emitters and thus destroyed all of the Asurans in the city before they had a chance to adapt.
Conflict with the New Atlanteans
The Asurans decided upon a different way of defeating the threat the humans posed to them. They began constructing warships on their homeworld believed to have the express purpose of fighting the humans in their home galaxy where Earth is located. This preparation was destroyed when the Apollo launched a surprise nuclear strike against the Asuran homeworld. With the devastation they faced, the Asurans began a new strike against Atlantis itself using a powerful energy weapon directed from an orbital satellite Stargate with the sole aim of destroying Atlantis. However, Sheppard was able to fly the city several light years away but dropped out of hyperspace early due to damaged inflicted that prevented sufficient power from reaching the city's stardrive. Using the reactivated nanites within Elizabeth Weir to access the Asuran datanet, a strike team was able to infiltrate Asuras and steal a ZPM. However, the Asurans eventually detected the team's presence, and managed to override the Anti-Replicator field that repelled them. Although Weir was able to fool the Asurans into thinking that they had captured the Atlantis team by planting a false scenario in their minds, thus giving the team an opportunity escape, she herself was captured. Meanwhile, Rodney McKay managed to isolate and reactivate the attack command embedded in the Asuran central core, thus compelling the Asurans to launch an attack against the Wraith.  It is later revealed in the next episode that the Wraith were the ones who turned the "attack-Wraith" subroutine off.
Initially, the war against the Asurans goes badly for the Wraith, who are taken by surprise. Later in the conflict, however, they manage to destroy two Asuran warships as they begin to regroup to fight this new threat.  However, the war spreads to the humans of the Pegasus Galaxy. The Asurans, knowing that the Wraith depend on humans as a food source for survival, have adopted the tactic of exterminating all human life in the Pegasus Galaxy. The Atlantis team realizes that their plan to reactivate the Asuran attack code has backfired, and begin working to create a new virus to shut down the Asuran attack code.
As the war continued between the Asurans and the Wraith, the faction of Asurans that sought Ascension recreated Atlantis along with John Sheppard, Teyla, Ronon Dex, Rodney McKay and Elizabeth Weir in order to learn what Human qualities allow for Ascension. This 'experiment' was done so secretly by this group but the dominant Asurans along with Oberoth discovered this and terminated the experiment along with the rogue Replicators. 
The Asuran warships are attacked by the upgraded Daedalus and Apollo in Be All My Sins Remember'd using the Aurora class vessel tracking device provided by the Asuran resembling Dr Keller in This Mortal Coil and a fleet consisting of Wraith, Travelers and Earth ships is assembled in an all out attack on the Asuran homeworld while McKay attempts a plan to rid the galaxy of the Asurans once and for all. The plan succeeds with all of the Asuran's nanite cells combined into a "amorphous" blob, sinking into the planet's surface and reacting with the native planet's large amounts of Neutronium and thus the Asuran homeworld is destroyed along with their technology with the exception of a single Aurora class vessel hiding within the remnants of the planet commanded by Dr. Weir along with a crew of Asurans.
The Asurans possess much of the knowledge of the Ancients, as evidenced by their manufacturing of ZPMs and by their creation of a near identical city-ship to Atlantis. They also possess the ability to directly interface with the human subconscious - just as the other human-form Replicators do - and the ability to walk through walls. It is also known that their strength is far superior to that of a normal human, as Oberoth was shown to lift Mckay with one arm and swat Ronon aside with little effort, again just like the other human-form Replicators.
Their interdependent organic constituents consist of over three billion chemical base sequences. EMP weapons are a threat to the nanites' base forms. However, they are somehow able to integrate organic technology into themselves to make them somewhat immune to this vector of attack .
The Asurans are actually made entirely of nanites that were created with the express purpose of fighting the Wraith. Eventually, it evolved into their current human-shaped form and their appearance is only a mask which hides the true nature, as well as abilities, of the Asurans. The nanites themselves are self-replicating machines that can survive as long as a minuscule amount functions. This makes them very resilient as a small number of nanites managed to survive orbital strikes from Lantean warships and were enough to continue their species. The nanites are capable of using any material for this task, be it mechanical or biological in origin.
The nanites provide them with several advantages, the first of which is that they can penetrate solid objects. This allows them to pass through doors via the smallest openings. Another ability is one they share with the other Human Form Replicators which is moving their hands within the skull of humans. The nanites allows the Asurans to experience the memories and knowledge of the person they are subjecting the 'interrogation' to though the pain suffered varies on whether the Asuran does the task in a brutal or kinder fashion. They are able to gain intimate details through this process and are quite capable of fashioning personalities based on the people they have mentally probed.  Whether they share the other Human Form Replicators ability (or more likely affinity) to fashion bladed weapons from their body parts is unknown currently.
A more sinister nature of the nanites is that, once in contact with a human body, they can be left in trace amounts which can be directed by the Asuran mind. The presence of such nanites within a human body can leave the human in a coma-like state while the Asurans mask themselves as being part of the immune system. The nanites work to circumvent the human mind while they use the human biology to incorporate organic components into their selves. This can potentially result in the birth of a new Asuran in quite a brutal fashion for the infected host. The infected body remains in a coma-like state, however, their minds are active and put through an imaginary world in order to lull the body into a compliant state in order to allow the nanites to continue their work. Somehow when Dr. Weir managed to overcome this by walking through an image of Niam in her mind and then Gating back to Atlantis the nanites in her system shut down. In Lifeline McKay said Weir exhibited some amount of control over them so its possible that this was a battle of wills and when Weir won she had at least some control over them and shut them off herself.
An interesting observation is that the nanites themselves in their smaller state are vulnerable to EM pulses however once they incorporate organic components within the system this weakness is quickly erased. In addition to this, the presence of Wraith tissue can result in the nanites to go immediately to the 'infected' part and exterminate the Wraith DNA. Though they appear to be intelligent enough to leave parts of themselves in certain locations in order to ensure that they survive..
Apparently at least some of those nanites survived deactivation as McKay reactivates them to save Dr. Weir's life. This has the side-effect of giving her access to the Asurans' subspace network (similar to how Teyla can tap into the Wraith's) and even allow her to use the mind-probe as she uses this on Oberoth in Lifeline to freeze him and the other Asurans to buy Sheppard and Ronon more time. Once activated Weir showed great control over them even managing to somehow override the kill switch and using them to act using the Asurans own abilities against them.
Mention is made when the Asurans manage to gain a foothold on Atlantis of disassembling their ship for additional parts to repair the city-ship. Whether this was done through their nanite means or other is unknown. However, it was done in a short span of time which suggests that they accomplish this feat at an extremely fast and efficient rate.
The Asurans are equally capable of using the nanites and programming them for other tasks. This can be seen in the recreation of Atlantis along with its flagship team and replicator Elizabeth Weir who were created through the use of nanites but were flesh and blood organisms with the memories of the originals. This task, however, requires a great deal of power to accomplish. 
Like their Replicator cousins, the Asurans are all tied to one another through a sophisticated subspace network that connects each and every member of the race. Despite this though, they seem to be somewhat more individualistic compared to the swarm mentality of the Replicators with each Asuran being an entirely independent entity. This is, ironically, very similar to the Wraith, the race the Lanteans created the Asurans to combat. The benefits of the subspace link allows the Asurans to keep up to date with anything another Asuran experiences. This allowed the race to realize the betrayal by Niam against their kind and allowed them to 'reset' him to his original state. As such, the link serves as a form of control mechanism for their kind and he was subsequently 'reset' which suggests that his more peaceful attitude was not always there but something learned during his existence and he was thus returned to his more aggressive root behavior.
Furthermore, the collective mind of the Asurans is capable of storing the essence of the different kinds of Asurans. This essentially allows a deceased Asuran to be replicated again, as was the case with Oberoth..
This collective will is also subject to periodic updates known as Merges where all Asurans are updated with new information that is disseminated among the various Asuran Replicators. Though this is the primary method of data being shared among the race, there exists a hard drive copy that exists outside in a physical form. This is seen in the presence of Central Data Core on their homeworld of Asuras.
In Lifeline, Elizabeth Weir gains access to this network after the nanites in her blood are reactivated to save her life. She uses the information she gathers from it to lead Lieutenant Colonel Sheppard and Ronon Dex on their mission.
The Asuran base code is the underlying program that governs the race and was created by the Ancient species when they first made the original nanite virus. In "Lifeline" its revealed that there are thousands of command directives present within the Asuran Base Code.
One of the important aspects of the base code prevents the Asurans from striking against their creators. They were also prevented from altering their own base code which severely limited their behaviour in regards to changing as a species. Another aspect of the base code prevented the Asurans from altering their appearance and taking the shape of other beings; essentially, upon creation, the Asurans had to remain in the form they were created in. However, the changes made by Rodney McKay allowed the Asurans a new ability to mimic the appearance of others. 
The programming, however, could be altered by other species as members of the Atlantis Expedition demonstrated. Unfortunately, this had the effect of allowing the Asurans access to their own base code and allowing them to alter it to suit their needs, such as altering the programming that prevented them from attacking their creators.
In Reunion, it's revealed that the Wraith have encountered and fought the Asurans in the past (how long ago isn't stated) and that the Wraith managed to shutdown the attack directive within the Replicator base code (which would normally force the Asurans to attack the Wraith). The Wraith attempt to shutdown the directive once again with a virus but weren't able to, possibly due to safeguards the Asurans put in place or Rodney's tampering. 
Terminating an Asuran
The Asurans' nanite makeup allows them to be very resilient to physical harm, and even weapons, whether they are projectile or energy, seem to have no way of harming them. Conventional guns appear to have minimal effect on them. Ronon's Gun, however, can temporarily stun them (as opposed to the original Replicators and Human Form Replicators, which were immune to any energy weapon used against them). Human-built 'knockoffs' of the Ancient/Asgard Replicator disruptor weapon have been designed to destroy them. As of the episode "Lifeline" the Asurans have built up an immunity to the human Anti Replicator Weapons. This was through sacrificing their numbers into an Anti-Replicator Field until the point they could overcome the weapon.
A single pulse from the weapon will reduce an Asuran into its component blocks by severing the connection that holds each block together, just like it does with their human form replicator cousins. However, just like there human form cousins, the Asurans can adapt to the frequency of the weapon and thus develop an immunity to its effects. In the concluding part of "The Return", it is also shown that the Asurans require some input of energy, which, after being denied a power source for long periods, makes them vulnerable and incapacitated. However, it only takes them a short amount of time to adjust and become a deadly threat once again.
As seen in the case of Oberoth, the Asurans are capable of replicating a destroyed member of their kind, thanks in part to their subspace link. This can effectively make members of this race immortal for as long as part of their race survives.
McKay eventually creates a means to defeat the Asurans by affecting the Asurans in the exact opposite way than the Anti-Replicator gun. Instead of disabling the attraction between nanites and making the Asurans turn into "dust", it makes all them extremely attracted to each other, creating a super-dense blob of nanites. By sending in a home-made Replicator with pre-programed nanites to the Asuran home world, McKay is able to make all the nanites come together in one super-dense "blob" that, due to being so dense, sinks through the planet to the core, reacting with it. This severely destabalizes the planet, in turn making it explode.
It was later shown that a single Asuran ship full of Replicators survived the destruction of the Asuran home world, with one of the Replicators resembling Elizabeth Weir.
Little is known of Asuran society and culture except that they have emulated the Ancients in appearance and technology. Most of them seem to bear a cold hatred towards their creators due to the attempted extermination of their race. They appear centered around their homeworld of Asuras, which is dotted by vast cities. They appear to be isolationistic and regard humans as lesser beings. They have shown no fear of the Wraith and even claim to possess a plan that could nullify the Wraith threat, though the details of this plan have not been revealed. Although, it could involve a plan they put into effect to destroy the Wraith's food source 'humans'.
Despite this, there does appear to be a small enclave among their kind that still admires and respects the Ancients. This group would go as far as imitate their makers to the fullest extent by Ascending. However, this group has met with little success in their endeavors, perhaps due to their programmed aggressive nature, which may be the only thing preventing them from achieving their goal. This does not appear to be a natural state as when Niam was reset by the Asurans, he reverted to a far more aggressive behavior than what he had previously displayed when Sheppard's team first encountered him. A majority of this group were reset but some survived within the Replicator collective and continue their attempts at finding the key to ascension. .
The vast majority, however, wish to continue in isolation until they encounter the Atlantis Expedition. After this encounter, the Asurans are determined to destroy the 'favored' children of the Ancients as a last act of revenge against their makers.
Asurans view humans as an inferior form of life and are willing to kill thousands, to destroy the Wraith, as seen in The Seer. They view the Tau'ri especially with envy and hatred due to the fact that they are from Earth, the homeworld of the Ancients, as well as the fact that many are direct descendents of the Ancients and now inhabit Atlantis.
Little is known of Asuran tactics but they seem to favor conventional manner of defeating opponents through the use of force and their advanced technology. It is known that when this is not available, the Asurans resort to other means of achieving their goals such as the deployment of a satellite weapon to destroy Atlantis.
When facing a threat that could destroy them, the Asurans have shown, as of Lifeline, to willingly sacrifice their number til they are capable of overcoming the problem. In the face of an Anti-Replicator Field, the Asurans sent forth pairs of their numbers into the field which killed the units until finally they were able to overcome the effects of the field.
Another demonstration of their Strategic thinking can be seen in the episode The Seer during the Asuran-Wraith War. The Asurans analyzed their enemy and have identified a crucial weakness among their Wraith foes: their dependence on the humans of the Pegasus galaxy as a food source. Seeing this, the Asurans' military might adapt to exploit this weakness by wiping out the human population of the galaxy in order to starve the Wraith, an efficient and much less costly approach then a direct confrontation with the Wraith themselves. It is possible that such tactics could have also been used during the Wraith/Ancient war 10,000 years prior, and would have been a strong contributing factor in the Ancients' decision to terminate the experiment.
The Asurans are perhaps one of the most advanced races within the Stargate universe and have owed much of this to their replication and imitation of the technology of their creators, the Ancients. While the Asurans are quite capable of building advanced Warships, quite probably duplicates of Lantean warships, they are vulnerable insomuch as the Warships are purely conventional technology. Unlike Replicator ships which are often partially or wholly made up of Replicator cells making them all but immune to energy weapons, Asuran ships are just as vulnerable to conventional anti ship weapons as Ancient ships...which given their sophistication, is not that much comfort given their Replicator-like industrial capabilities.
Presumably, they are named for the Asuras of Hindu (or simply Indo-European) mythology, who were the arrogant and violent adversaries of the rulers of Heaven, the Devas, much as the Asurans are with regards their creators, the Ancients. However, in Vedic Hindu mythology the Asuras are simply the guardians of the law, whereas the Devas are the guardians of life, although this definition doesn't seem to apply.
However, unlike the impersonation of Egyptian, Greek, Chinese, and various other cultural deities by the Goa'uld, the Asurans do not appear to be based on or the basis for any race in Human or Lantean mythology, so their naming is quite likely an arbitrary one by the show producers.
- "Reunion". Stargate Atlantis. Cite error: Invalid
<ref>tag; name "progeny" defined multiple times with different content Cite error: Invalid
<ref>tag; name "progeny" defined multiple times with different content
- "This Mortal Coil". Stargate Atlantis.
- "The Return Part 1". Stargate Atlantis.
- "First Strike". Stargate Atlantis.
- "Lifeline". Stargate Atlantis.
- "Tabula Rasa". Stargate Atlantis.
- "The Real World". Stargate Atlantis.
- "This Mortal Coil". Stargate Atlantis.
- "Reunion". Stargate Atlantis.
- "All My Sins Remember'd" (2007)