Sentinels

"There is a new enemy out there: mutants. You need a new weapon for this war."

- Bolivar Trask

Sentinels were robots created with the sole purpose of destroying mutants.

X-Men: Days of Future Past
In 1973, Bolivar Trask pitched the Sentinel Program to Congress but they declined him so he pitched them to foreign powers instead such as Vietnam and China.

X-Men: Days of Future Past
Mystique then killed Trask in Paris as revenge for all the mutants he had killed. She was taken in, tortured and experimented on. The Sentinel Program was then greenlit and eventually Mystique's DNA was used to make the Sentinels unstoppable.

X-Men: The Official Game
To be added

X-Men: The Last Stand
A Sentinel is used as a simulation in the Danger Room in order to train the young X-Men in team play. The robotic behemoth attack Kitty Pryde, Rogue, Colossus and Iceman, with Wolverine and Storm as the team leaders. The young mutants only manage to defend themselves against the Sentinel's attack, with Logan smoking a cigar at a distance, complaining about how boring the task of a teacher is. When an explosion makes Wolverine lose his cigar, he gets angry and makes Colossus throw him towards the Sentinel, decapitating it with his claws and putting an end to the simulation.

X-Men: Days of Future Past
Trask Industries finally developed Mystique's DNA and replicated it into the latest Sentinels. The Sentinels began taking over the world in order to destroy the mutant threat. At first the Sentinels only targeted mutants which were either terminated or sent to Mutant Concentration Camps, then they targeted regular humans who had a chance of having the mutant gene passed on to their children, grandchildren, or great grandchildren. Some humans attempted to rebel and save mutants but those were also targeted, leaving only the worst of humanity left to rule.

While the mutants were nearly extinct, the powerful ones survived and continued to fight the Sentinels such as the Free Mutants group lead by Bishop and the X-Men lead by Charles Xavier and Magneto. In a final effort to win the war, Kitty Pryde sent Wolverine's consciousness back in time to stop the Sentinel Program from ever being activated.

X-Men: Days of Future Past
Mystique attempted to kill Trask in revenge for the murdering mutants while creating the Sentinels, not knowing the future this will create. She was interrupted by Charles Xavier, Beast, Magneto and a time-travelling Wolverine who were attempting to prevent the destruction caused by the Sentinel project's completion.

Unfortunately, the fight with Mystique exposed mutants to the world and President Nixon agreed to the Sentinels' use while Mystique's blood was collected from where she was wounded, allowing the Sentinels of the future to have her powers. Magneto, both to stop the Sentinels and to use them to take over the world, surrounded them in steel, allowing him to control the Sentinels at their unveiling on the White House lawn. Magneto used the Sentinels to attack the crowd and hold off Wolverine, Xavier and McCoy, but before he could kill what he believed to be Nixon (really a disguised Mystique), McCoy suppressed his mutation with a serum causing a Sentinel to turn on Magneto. He quickly disabled it, but the distraction allowed Mystique to shoot him with a plastic gun, wounding him and then knock him out, deactivating the Sentinels. After Xavier convinced Mystique through telepathy to let Trask live, the world saw that a mutant saved the President and the Sentinel program was shut down and Trask was arrested for selling military secrets to foreign powers, erasing the dystopian future.

Types

 * Mark I
 * Mark X

Powers and Abilities
The Sentinels are gigantic robots, originally three times the size of a human. The Mark I were crude and bulky and with more limited mobility. The ones from the future, the Mark X, were considerably more advanced, being made of synthethic skin with a more streamlined and flexible body. All versions of the Sentinels were made from a unique polymer, free of metal, making them immune to Magneto's powers.
 * Superhuman Strength: The Mark X, possessed immense physical strength, enough to break through solid materials such as thick ice, stone and metal aswell as physically overpower mutants such as Sunspot, Iceman and even Colossus with ease. Two Sentinels were strong enough to rip Colossus in half and one managed to decapitate Iceman despite him being in his ice form.
 * Superhuman Speed and Agility: Despite their size and bulk, the Sentinels are remarkably fast and agile, enough to outmaneuver the mutants, perform mid-air flips and climb the side of a mountain quickly and with ease.
 * Superhuman Durability: One of the Sentinels more phenomenal capabilities is their capacity to sustain damage. Even without their powers of minicry, they can endure strikes from Colossus, one of the most physically powerful mutants and resist sustained ice and fire streams from Iceman and Sunspot respectively.
 * Flight: The Mark I Sentinels could fly using the vent-like sytems on their chest. The Mark X could also fly.
 * Mutant Detection: Sentinels are equipped with sensors that allow then to track carriers of the X Gene, such as mutant or even  people who could have mutant offspring. This allows them to hunt mutants anywhere in the world and they will not stop until they have eliminated their target.
 * Machine Guns: The original Sentinels, the Mark I, possessed gatling guns on one of their arms, capable of firing 3000 rounds per minute. This was not present in their future counterparts.
 * Laser Beam: One of the Sentinel's main offensive weapons, they open the front of their heads to reveal an orb of energy that can fire extremely potent and sustained energy blasts, capable or melting through anything.
 * Shapeshifting: Due to their unique composition, created from the reverse engeneering of the capabilities of Mystique, a shapeshifting mutant, Sentinels can alter their bodies to fit a variety of purposes. Most commonly, they are seen altering the shapes of their arms into extremely sharp blades and claws. Also when innactive, they take on a smaller form for transportation.
 * Mimicry: The most powerful ability of the Sentinels, they can use the powers of other mutants. They were mostly seen altering their bodies into forms almost identical to those of Colossus, Sunspot and Iceman in order to counter them. The also used powers similar to Emma Frost, Darwin, and Lady Deathstryke. It appears that a Sentinel needs to be exposed to the enemy mutant's powers for a bit of time before this ability is activated. They are also capable of sharing newly copied powers and abilities with other Sentinels.

Relationships

 * Bolivar Trask - Creator.
 * William Stryker - Creator.
 * Mutants - Enemies.

Behind the scenes

 * Although Sentinels were set to appear in every X-Men movie, they never did. However, some sketches of their rendering for X2: X-Men United appear on the DVD extras. They appear almost the same as in the comics, with the exception of a compact form they were meant to use for transportation.

Trivia

 * In the videogame tie-in between X2: X-Men United and X-Men: The Last Stand it is revealed that Sentinels were created by William Stryker as a part of his Weapon X project, with Bolivar Trask and HYDRA financing their construction.
 * Sentinels were supposed to appear in X-Men, used by William Stryker and Henry Gyrich against The X-Men, but they didn't go beyond the first draft.
 * Sentinels were planned to appear in X2: X-Men United, but were cut. A sign of them can be seen on one of William Stryker's computer, in which "Project Wideawake" appears.