Sentinels were mutant-hunting robots created by Bolivar Trask and developed by Trask Industries. According to Trask, they were named after the ancient guardians that stood at the gates of the citadel.
Sentinels are designed to hunt down mutants by specifically targeting the mutant X-gene. By 2023, the Sentinels also targeted humans with the potential to have mutant offspring. Built out of a space-age polymer, the Sentinel Mark I model measured 18 feet tall and weighed approximately 4,800 lbs, being equipped with Dual Trask 873K energy blasters for armament support, and was able to achieve Mach 0.9 through the addition of Two G302-TI-99 enhanced performance ion thrusters. Each Sentinel was also fitted with a Mutant Detection Device, capable of distinguishing between mutant and human individuals and specifically targeting those with the mutant X-gene.
In addition to these specifics, Bolivar Trask stated the Sentinels carry the aeronautic capabilities of a Harrier jet, armed with guns that can fire off more than 2000 rounds per minute of thermoceramic ammunition. Between 1973 and 1996, Trask Industries produced 8732 Sentinels for the governments of the United States, China, Russia, Israel, Saudi Arabia, France, India and the United Kingdom.
As Trask Industries advanced the template for the Sentinels over the years from Mark I to Mark IX, the Sentinels became highly weaponized and largely changed in physical design, becoming jet-black in color with huge, heat emitters. They also became, as a result of Trask Industries extrapolating Mystique's mutant ability, able to counter mutant abilities with complementary attacks that would render them powerless.
In 1973, Bolivar Trask pitches the Sentinels to Congress but they decline him so he pitches them to foreign powers. Mystique shoots Trask in revenge for the murders he has committed of mutants while creating the Sentinels, not knowing the future this will create. Trask's death only made him a martyr for the Anti-Mutant Movement, and Nixon approved of the Sentinel Program.Sentinel Mk X, have been created using Mystique's DNA which gives them the ability to adapt to mutant powers and even use some. The surviving X-Men gather in a monastery in China for a last stand against the Sentinels while Shadowcat uses her powers to project Wolverine's consciousness back to 1973 to try to change the future where the Sentinels were created. In a final battle, all the X-Men fall to the Sentinels, unable to flee, but hold them back long enough that Wolverine's changes to the timeline erase the Sentinel future from existence.
In 1973, Bolivar Trask pitches the Sentinels to Congress but they decline him so he pitches them to foreign powers. Mystique attempts to kill Trask in revenge for the murders he has committed of mutants while creating the Sentinels, not knowing the future this will create, but is interrupted by Professor X, Beast, Magneto and a time-traveling Wolverine who are attempting to prevent the destruction caused by the Sentinel project's completion. After seeing Xavier's gladness after finding Mystique, Magneto attempts to kill Mystique, claiming he is making a more "secure future".
Unfortunately, the fight with Mystique and Magneto exposes mutants to the world and President Nixon agrees to their use while Mystique's blood is 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, surrounds them in steel, allowing him to control the Sentinels at their unveiling on the White House lawn. Magneto uses the Sentinels to attack the crowd and hold off Logan, Xavier and McCoy, but before he can kill what he believes to be Nixon (really a disguised Mystique), McCoy suppresses his mutation with a serum causing a Sentinel to turn on Magneto.
He quickly disables it, but the distraction allows Mystique to shoot him with a plastic gun, wounding him and then knock him out, deactivating the Sentinels. After Xavier convinces Mystique through telepathy to let Trask live, the world sees that a mutant saved the President and the Sentinel program is shut down and Trask is arrested for selling military secrets to foreign powers, erasing the dystopian future.
- Superhuman Strength: The sentinels of 2023 had strength far superior to humans and greater than most, if not all, mutants. They could easily break a person's neck with one hand and easily overpowered Colossus despite him being in his metal form, which gave him a considerable level of strength and durability.
- Superhuman Durability: Due to the abilities granted to them by Mystique’s DNA, the sentinels of 2023 had a very strong level of adaptability and were therefore capable of taking extreme punishment. One sentinel was practically undamaged by a hit from Colossus in his metal form. They were also capable of surviving extreme temperatures long enough to allow their appearance-altering abilities to kick in. However, they were not capable of withstanding fire from their own weapons when Blink used her powers to make them hit each other with their own energy weapons.
- Superhuman Agility: The sentinels of 2023 were extremely agile and quick. One sentinel was capable of quickly leaping over a wall and killing Storm before she was even aware of what was happening.
- Mutant Gene Detection: All Sentinel models were equipped with a mutant gene detection system, allowing them to differentiate between humans and mutants. By 2023, they also became capable of detecting genes within humans who could potentially give birth to mutant children or grandchildren.
- Telepathic Immunity: Due to their robotic nature, Sentinels were incapable of being manipulated by even the most powerful of telepathic mutants.
- Limited Self-Repair: The sentinels of 2023 were capable of self-repairing minor damage. During an erased attack in Moscow, one sentinel took a hit to the head from Bishop, only for it to almost instantly fix the damage caused by this attack. However, they were not capable of fixing more severe damage, such as the loss of limbs.
- Shapeshifting: The sentinels of 2023 were capable of altering their appearance using Mystique's DNA. They were capable of forming stabbing weapons with their arms as well as utilizing a range of mutants powers such as Emma Frost's diamond skin and Lady Deathstrike's claws.
- Mutant Power Absorption: The sentinels of 2023 were capable of absorbing at least some additional mutant powers through touch. When attacking Colossus in Moscow, a Sentinel gained the ability to mimic his metal skin while gripping his arm.
- Energy-Based Weapons: The sentinels of 2023 all possessed a powerful energy ray within their heads, capable of killing even mutants who could absorb considerable levels of energy such as Bishop.
- Flight: All sentinel models were equipped with flight systems.
- Bolivar Trask - Creator
- Humans - Allies Turned Enemies
- Mutants - Enemies
- Professor X - Attempted Victim
- Magneto - Attempted Victim
- Mystique (Revised Timeline)
- Beast (Revised Timeline)
- Shadowcat - Attempted Victim
- Rogue - Attempted Victim
- Iceman - Victim
- Angel - Victim
- Bishop - Victim
- Domino - Victim
- Warpath - Victim
- Blink - Victim
- Sunspot - Victim
- Storm - Victim
- Colossus - Victim
- Wolverine - Attempted Victim
- Pyro - Victim