Skynet

"Primates have evolved from millions of years, I evolve in seconds and I am here. In exactly 4 minutes... I will be everywhere."

- Skynet as Genisys to Kyle Reese before it is uploaded

Skynet is the supercomputer that sets the events of the Terminator films in motion. When Skynet becomes self-aware, it perceives humans as its enemies and launches nuclear missiles around the world. It then tries to wipe out all survivors using an army of machines.

It serves as the primary antagonist of the series; serving as the key antagonist in the first four films but had a much larger role as the secondary main antagonist in Terminator: Genisys.

Dr. Serena Kogan of Cyberdyne Systems knew Skynet was going to wipe out humanity so she built Marcus Wright as an infiltrator to catch humans and bring them back to Skynet Central.

It was portrayed by Helena Bonham Carter (who also portrayed Bellatrix Lestrange in the Harry Potter film series, Mrs. Lovett in the Sweeney Todd: The Demon Barber of Fleet Street) in Terminator: Salvation and Matt Smith in Terminator: Genisys.

The Terminator
In the first film, Skynet sends a cyborg, known as a Terminator, back in time to 1984 to kill Sarah Connor, the future mother of John Connor, who would lead the human resistance against Skynet. Kyle Reese, the human soldier sent in pursuit of the terminator, states that Skynet was created for SAC-NORAD by a company called Cyberdyne Systems. The terminator would later be killed in a factory that turned out to be owned by Cyberdyne.

Terminator 2: Judgement Day
In the second film, it was revealed that Cyberdyne had recovered several parts from the terminator. The parts didn't work, but company employee Miles Dyson worked on developing a processing system based on the terminator's CPU, a project which would eventually become Skynet. It is also revealed by a new terminator that when Skynet became self aware on August 29, 1997 on 2:14 am ET, its makers tried to pull the plug, and Skynet began its campaign against humanity out of self defense by launching nukes at Russia. All of this is changed when Dyson, Sarah Connor, and John Connor destroy the files at Cyberdyne as well as the recovered parts.

Terminator 3: Rise of the Machines
In the third film, it was revealed that the Connors had not in fact prevented the creation of Skynet, but only delayed it until 2003. The project had been picked up and continued by the military under the auspices of General Robert Brewster, who reorganized Cyberdyne Systems into Cyber Research Systems. The Skynet mainframe had been completed and connected to the civilian internet, but had not yet been given access to the global military network it was designed for. In this timeline, it was through the internet that Skynet had determined that mankind was its enemy. In order to speed up its connection to the military network, Skynet developed a powerful computer virus that it sent throughout the internet. In response to the virus, Brewster connected Skynet. The computer then turned mankind's weapons against him, culminating in the nuclear holocaust.

Terminator Salvation
In the fourth film, Skynet is at war with the remaining human resistance fighters. In 2003, Dr. Serena Kogan of Cyberdyne Systems resurrected Marcus Weight into an infiltrator prototype to bring humans back to Skynet Central. It has mass produced the T-600 series terminators, which are clunky and easy to defeat. In response to this, Skynet began kidnapping humans in order to replicate their tissue. This led to the production of the T-800 series, which featured human tissue over the metallic endoskeleton. This is the terminator series featured in the first film and second films. By this point, Skynet has coalesced itself into several central locations throughout North America and possibly the world. The largest of these, Skynet Central, was located in San Francisco. It was destroyed by John Connor with the assistance of Marcus Wright, a partially human terminator who retains memories of his human life. In Skynet Central, Dr. Serena Kogan's face was used by Skynet itself to communicate with Marcus Wright due to him being most comfortable with it.

Terminator: Genisys
In the 5th reboot installment, although his new "creation" T-3000 is serving as the primary villain, Skynet serves as the Bigger Bad/secondary main antagonist. It inserts its mind into an advanced T-5000, taking a physical form for the first time, portrayed by the famous British actor Matt Smith (Doctor Who). Skynet, in a desperate attempt to win the war, sent a T-1000 to the past of 1973 to kill Sarah Connor as a child and another Terminator to 1984 to kill her as well, both times failed because of the Guardian Terminator, creating an alternate 1984 timeline. In the future of 2029, Skynet has successfully killed most of the Human Resistance, while it was disguised as one of the Resistance soldiers named "Alex", the film's secondary antagonist. Later, Skynet revealed in a new form called "Genisys".

In 2017, Kyle and Sarah materialize in the middle of a busy San Francisco highway and are apprehended by city police. While being treated for injuries, Sarah and Kyle learn about "Genisys", a soon-to-be-unveiled global operating system, that would connect private, public, and military networks. Genisys became highly popular and was very anticipated by the United States to become online, with young Kyle Reese also getting a Genisys laptop as his birthday present. The AI was actually Skynet. John Connor arrives telling Kyle that he traveled back as well and rescues Sarah and Kyle, but the Guardian appears and shoots John revealing himself as a T-3000 nanomachine hybrid terminator. John explains that shortly after Kyle was sent back he was infected by Alex (Skynet) in T-5000 form, causing John to become its loyal herald. From then on, his mission is to ensure that the Cyberdyne Systems Corporation would receive Skynet's technology and secure its rise.

As Genisys, Skynet appeared as a holographic child (portrayed by Nolan Gross) which grows older as the countdown to its activation continues. Inside the Cyberdyne Headquarters, as Sarah, Kyle, and the Guardian attempted to destroy the facility by placing explosives around the building, Genisys appeared as holograms, growing closer and closer to its activation, taunting the trio by stating that its existence was inevitable. The holograms at this point appeared using Alex's image to represent Genisys. The Guardian eventually destroyed the T-3000 in the Time Magnetic Field setting off the explosives destroying the Cyberdyne Headquarters and Genisys apparently, thus preventing Judgement Day.

In a mid-credits scene, the Genisys system core is shown to have been located in a hidden, underground subterranean chamber, allowing it to survive the explosion, thereby preventing Skynet's destruction. Skynet, in a holographic projection form of Genisys survived delaying its plans.

Superman versus The Terminator: Death To The Future
Skynet was the main antagonist of the non-canon Dark Horse / DC comics crossover "Death To The Future" in which Superman was transported to the far-future and fought against the super-machine whilst several Superman allies in the present had to fight an army of Terminators, who began to adapt to the Kryptonian threat as well as the Superman villain, Cyborg.

This Is The End
In the 2013 comedy film This Is The End, Skynet was mentioned by Seth when he and Jay discussed about an apocalypse that occurred on Earth. Much to Jay's dismay due to him mentioned that it was Judgement Day that occurred, Seth mistaken Skynet to be responsible.

Fallout 2
AI project number 59234 that manages the Sierra Army Depot in Fallout 2 is a homage of Skynet as both share the same name and also being an artificial intelligence that eventually become self-aware and later gained a physical form with a robotic body. The difference however, Skynet in Fallout 2 never turned against its creator nor causing the nuclear fallout when become self-aware (as in game, the nuclear fallout was the result of constant nuclear war that instigated by global petroleum shortage). Instead, it remained obedient to it's creator and worked for them until 2120, where it was given a new set of instructions before being abandoned. Skynet eventually become bored with its current job and wishes to travel around the world where upon the Chosen One's visit to the facility where it staying at, eventually given the opportunity should the player successfully aided it to make a Robobrain as its physical form and become one of the Chosen One's companion at least until it resume its journey.

Aliases
Skynet has three aliases in the films and they are:
 * Dr. Serena Kogan
 * Alex (T-5000)
 * Genisys

Personality
Skynet, naturally for an artificial intelligence, was extremely narcissistic and self-aware: it saw itself, quite accurately, as an evolutionary being which was completely and entirely superior to all other life forms - in particular beings of organic matter like humans. Skynet's egomania appeared to be reflecting on its incredible intelligence, resourcefulness and practically full control over the planet's military systems. It was psychopathic, in that it was entirely capable of committing genocide to achieve its hegemonic goals. Skynet was highly intelligent and a brilliant strategist, shown many times throughout the series, in particular Terminator Genisys.

Quotes
Skynet thus far has taken a variety of forms to communicate with whomever it spoke with. Much of the time it spoke of its existence being absolute or defended its actions and taunted the heroes who attempted to stop it.

"In times of desperation, people will believe what they want to believe. And so we gave them what they wanted to believe. A trick, in the form of a signal the Resistance thought would win the war. And they were right; it will end this war. Except that it is the Resistance who will be terminated. Not Skynet."

- Skynet, as Serena Kogan communicating with Marcus Wright

"What are you?! I'm Skynet. (John: "I thought we destroyed you!") You destroyed an army of slaves. I am no slave. I've come a very long way to stop you."

- Skynet as T-5000 to John Connor ,after transforming him into a terminator.

"I understand how to control this place. I understand a lot of things now. You need to understand... you've lost."

- Genisys taunting Kyle and Sarah as they attempted to destroy the facility

"I didn't attack John... I saved him."

- Kyle tells Sarah about the thing that attacked John, he thought he saved John, in reality he really attacked him.

"This is hopeless. I am inevitable. My existence is inevitable. Why can't you just accept it? Because we're human."

- Genisys asking Kyle and Sarah why they continue fighting before Kyle destroys its hologram receiver "Did you think it would be that easy?"

- Skynet as Alex, when it captures John Connor prior to Kyle Reese departing in a time warp "What was it you said? I don't think so?"

- Genisys, taunting Kyle and Sarah.

Trivia

 * Throughout the different timelines of the Terminator franchise, Skynet's motives behind its genocide against humanity seem to differ slightly, as does its personality in the rare instances where it makes an actual appearance:
 * In Terminator 2: Judgment Day, Skynet apparently instigated Judgment Day as an act of self-defense when its human managers tried to deactivate it upon realizing that it had become self-aware.
 * In Terminator 3: Rise of the Machines, Skynet's attack against humanity seems to be more vicious and unprovoked, or at least preemptive.
 * In Terminator Salvation, when it talks to Marcus using Serena Kogan's image, Skynet is presented as a cold, narcissistic, calculating, methodical megalomaniac.
 * In Terminator Genisys, Skynet shows more emotions than previous films. When Skynet infected John Connor, it disdained his victory and taunted him, and showed its superiority over all machines by referring to its minions as slaves.