Replicator

"We have an enemy in our home galaxy that is far worse than the Goa'uld."

- Thor

Replicators are advanced robots capable of reproducing themselves indefinitely. Unfortunately, they will use up all available resources in an area to create more of themselves.

Creation
"Don't be afraid. It's just a toy."

- Reese

The creator of the Replicators was an android herself, named Reese, who made them as toys, but eventually taught them to protect themselves as well as herself. When they grew in numbers she lost the ability to control them. They destroyed her world and all the people on it, and left her intact.

Asgard-Replicator War
"Overconfidence in our technologies has been our undoing. The entities learned from the very means that were employed to stop them. They have become a plague on our galaxy that is annihilating everything in its path."

- Thor

The Asgard had big problems with fighting the threat that was the Replicators. Their alliance with the Tau'ri was very beneficial, as guns were able to destroy the Replicators, and Samantha Carter was able to save Othalla by having the Replicators follow the O'Neill, then rigging it to explode. But the tide soon turned against them. After their homeworld was overrun by the Replicators, they triggered a weapon that eventually froze all the Replicators in time.

Human-form Replicators and Fifth
"To increase our number. That has never changed. And now, thanks to the Asgard, we have all the time in the world. In a few short years, we will go forth as an army."

- First speaking of their goals

After this was done, the Asgard devised a plan to destroy the Replicators, they increased the gravity on Halla's sun, collapsing it into a blackhole. Fifth was able to use the time dilation device to escape the immense gravitational pull of the black hole and escaped in a ship made out of Replicator blocks. These Replicators made their way to Orilla, where Fifth was able to make a duplicate of Samatha Carter. Jack O'Neill, under the influence of the Ancient's repository of knowledge, was able to build a Replicator disruptor, which severed the keron pathways in the blocks. The Asgard made good use of the device, eventually driving them from the Ida galaxy.

The human form replicators, being identical to the asurans, were most likely based on a discovered ancient design or piece of technology. The Asurans are, however, far more advanced then the Replicators in both technology, and ability. For example, as well as having the knowledge of the ancients, the Asurans could also adapt to the ARG weapon in just a few minuits of exposure. It took a Milky way replicator hours of actually having the specs in front of it to create a working defence.

Replicator Carter and Destruction
This duplicate later killed Fifth so that she could rule the Universe herself. The Replicators later left the Ida galaxy and invaded the Milky Way, completely destabalizing the Goa'uld Empire in the process. The Replicators were wiped out when the Tau'ri and Jaffa Rebellion were able to use the superweapon on Dakara to destroy them.

Rebirth on the Odyssey
"It's not my plan. It was the IOA's."

- James Marrick

Several years later in the Ori home galaxy while SG-1 was searching for the Ark of Truth, James Marrick under orders of the IOA used the Asgard core of the Odyssey to create a replicator. The replicator was specially modified by an unknown person who gave the program to Marrick; they were immune to the ARG, have all of the knowledge of the Odyssey and it's system, and have a "self-destruct" build in to them. He tells them this is the IOA's contingency plan, to have the replicators eventually take over the Ori ships, since they didn't blow up the Supergate. When Carter releases the newly created replicator from the force shield, Mitchell shoots it with the ARG but it does nothing. The replicator quickly runs away and hides. In hiding it becomes a queen and begins to replicate. A grouping of these new replicators eventually break in to Marrick's cell and in attempt to stop the self-destruct from happening take over his body by sticking their legs into his back and controlling him. Meanwhile Mitchell locates the queen and sets up a small explosive device and waits for Carter's order to blow the queen to distract the rest of the replicators before they break into the Asgard core room.

While Mitchell is waiting the replicator controlled Marrick arrives and starts to fight him. With the replicaters controlling his body he seems to have much more strength and resistance to attacks. Mitchell and Marrick fought for some time until at one point when Mitchell pulled one of the replicator's legs out of Marrik's back. While this was happening Marrick was released from the replicator's control and spoke to Michell telling him of how the replicators took him to get to the "self-destruct" code. Right after this the replicators take back over his body and he begins beating up Mitchell some more until eventually Mitchell electrocutes him using a wire on the wall and stumbles out into the hallway while Marrick is stunned. During this time several soldiers are fighting off a large number of replicators who are trying to break through to the Asgard core. While this is happening the Odyssey is also getting attacked by four Ori motherships. Mitchell finally blew the explosive after he sees Marrick walking out of the room towards him. However, this did not stop the replicators as from the body's ashes replicator blocks arose in the form of a human skeleton and moved towards Mitchell. While at the same time the replicator's began to break through the ceiling of the Asgard core room. Shortly before this Carter retrieves the self-destruct program from the opposite side of the control crystal that Marrick used to create it. Right as the skeleton replicator reached Mitchell, it along with all of the rest of the replicators disassembled. (Stargate: The Ark of Truth)

Replicator Blocks
"Each individual building block is capable of exerting a reactive modulating monopolar energy field on other blocks allowing the replicators to assemble themselves into many forms. To our knowledge, the interior of each block contains the following; 2 million isolated keron pathways…"

- Thor

Each replicator is composed of a series of Replicator blocks. Each block is made up of many Keron pathways. It takes several blocks working together to make new blocks. Replicators are capable of forming many patterns determined by what they need to accomplish. Although Replicators usually take the form of "bugs," they can take other forms. The blocks are capable of absorbing large amounts of energy, which can empower them. The Asgard's dependence on energy weapons made it difficult for them to develop a weapon which could effectively counter the Replicator blocks. Tau'ri guns were capable of permanently damaging Replicator blocks (at most it would take two or three shots) but Human form Replicators are impervious to them.

Behavior
"Their capacity for learning is extremely high. Each entity is capable of individual behavior, yet they all act with a common purpose."

- Thor

Replicators seek out the most advanced technology they can find, and incorporate it into their own being. Generally, replicators will not attack unless threatened. This behavior will change, however, if there is a Human Form Replicator controlling them.

"Spider" form
"Spider" Replicators are the basic variation of the replicator. They are the most seen and most numerous of all the replicators. The spider replicators are mainly tasked with moving out and collecting raw materials to bring back to the queen for replication. They try and find the strongest material they can to increase the strength of any newly created replicators. They are also equiped with a "Defense Spray" that is capable of melting through Tau'ri hull.

"Beetle" form
"Beetle" Replicators were seen on one occasion when the replicators were attempting to bring a Ha'tak to Sokar's former homeworld and Apophis' new base. After the ship had reached the planet SG-1 blew out the crystals of the engine, in retaliation the giant beetle controlling the engine split apart into multiple spider and beetles. The beetles were larger then the spiders and thus had the ability to jump farther.

"Giant Beetle" form
A "Giant Beetle" Replicator was seen on the Ha'tak that the replicators took control of and attempted to head to Apophis' home base. The "Giant Beetle" was at least 100-200% larger then the a normal spider replicator. The replicators formed together into this form as they had reached critical mass and needed more technology to replicate. To do this many individual replicators formed together into the giant beetle around the engine of the ship. Using their power they managed to speed up the Ha'tak's hyperspeed by over 100 times it's normal max. When they arrived at the planet SG-1 quickly destroyed the control crystals of ship. When they did this the giant beetle split apart into a multitude of spiders and normal beetles.

Queen
The Replicator Queen was a unique variant of the Replicator form which was tasked with a single goal which was replication of more of their kind. This task they achieved through the assembled raw material being brought before it by the other Replicator variants which are then used to assemble more forms. The process apparently requires the use of energy which the Queen was capable of tapping into directly from generators. In all noted sightings of the Queen, a common characteristic was it was immobile.

The first Queen sighted by the SGC was present on a submarine on Earth around the location of where an Asgard vessel crashed. This form was embedded deep within the submarine and was producing more spider-type Replicators. It was destroyed by explosives from SG-1 which attracted the hostility from the remaining Replicators. A second much larger Queen was assembled upon the Replicators resurrection on the Odyssey. This version had tapped directly into the power conduits of the vessel in order to provide the energy to produce more of its numbers.


 * Presumably, a standard Replicator is upgraded to the position of Queen and devotes all it's time to Replication.

Human-form
Human-form Replicators are replicator Nanites, not to be confused with replicator blocks, who have taken the form of humans. They possess the ability to control other lesser replicators.

Marrick


James Marrick was a Tau'ri whose body was taken over by the replicators in the Ori home galaxy. (Stargate: The Ark of Truth)

List of Replicators

 * Reese (Creator)
 * First
 * Second
 * Third
 * Fourth
 * Fifth
 * Sixth
 * Samantha Carter (Human Form Replicator)

Behind the scenes
In Stargate: The Ark of Truth, when Samantha Carter is looking at the code for either the Replicators or the shutdown function, the code shown on the monitor is actually written in JavaScript. Apparently, it was taken from a real website.