William Stryker is a military scientist who has a dislike of mutants and plans to rid the world of them.
Stryker was slightly altered for his film interpretation in X2. He is no longer a religious extremist, but a military scientist who has gone into defense contracting. His connection to Wolverine is made more explicit, as is his motivation regarding his son. Also, rather than having killed his son, Jason (who himself is partially modeled after Mastermind, another X-Men foe), at birth, Stryker sent him to Xavier's school in hopes of curing him, regarding mutation as a disease that must be cured. Xavier had no interest or belief in 'curing' mutants, which angered Stryker. Additionally, Jason continued to grow angry, resentful, and vindictive towards his parents; he tortured them by planting illusions in their brains until his mother committed suicide by drilling into her own brain in order to "bore the images out." Stryker then gave his son a lobotomy to make him more docile.
Jason, under his father's direction, brainwashes Xavier into using a reproduction of Cerebro to kill all mutants. Xavier and Magneto learned that Stryker is the mastermind behind an assassination attempt on the President by a brainwashed Nightcrawler. Magneto, wearing a helmet designed to shield against telepathic attacks, is able to reach Xavier while the X-Men are incapacitated by the psychic assault, but then has Jason make Xavier use Cerebro II to kill ordinary humans. At his direction, Mystique impersonates Stryker and instructs Jason of a change in plans, which Jason then communicates to the brainwashed Xavier. Magneto and Mystique escape, and soon thereafter Storm and Nightcrawler enter Cerebro II and disrupt Jason's illusion, allowing Xavier to break free from his control before any humans or mutants are killed. Stryker attempts to escape, but his attempts are foiled by Wolverine, then Magneto, and he is chained to a large block of debris. Stryker remains chained as the nearby dam bursts, implying he was killed in the ensuing flood.
In his last moments, he confronts Wolverine about how he apparently volunteered to have the adamantium put in his skeleton, and asks him whether he would actually side with mutants (implying that Wolverine originally hated his mutation before his amnesia). Looking at the young mutant he was carrying to safety, a young boy with a lizard-like tongue (Artie Maddicks), Wolverine informs Stryker that he would "take his chances with him" and left him to die. As Wolverine walks away Stryker says to him that "one day someone will finish what I've started. One day!"
X-Men Origins: Wolverine
In X-Men Origins: Wolverine, Stryker organised a team of mutants called Team X. The team members are Wolverine, Sabertooth (Wolverine's step-brother, also with healing powers but nails that can cut through metal), Agent Zero (a gunner who never misses), Deadpool (an expert "ninja" with quick reactions, reflexes, swords and guns), Bolt (a mutant who can control electricity, but cannot shoot it out), Wraith (a teleporter) and Blob (an indestructable mutant who is resistant to bombs and bullets).
But after a mission which involved finding Adamantium, an indestructable metal, Wolverine broke up with the team, despite Sabertooth warning: "We can't just let you walk away."
Wolverine moved to Canada and married. But one day, Stryker tracked down Wolverine and told him the team broke up after he left, but a mysterious killer is trying to kill the former team members of Team X one by one. The killer had already killed Bolt. Stryker asked him to help him find the killer, who he suspects the killer is one of the former team members. Wolverine refused, telling him that he already had a job and a wife in Canada.
After seven years in Canada, Wolverine found his wife dead, with claw marks as evidence. Wolverine immediately knew it was his step-brother, Sabertooth, and found him. Sabertooth calmly admitted he was the killer, and then Wolverine attacked him, furious. They had a fight, but Sabertooth won and injured Wolverine. Then Wolverine went unconscious.
When Wolverine went back conscious, he found himself in a hospital. Stryker was there, too. Wolverine got up and strangled him, saying "Why didn't you tell me it was him [that he was the mysterious killer]?!?" Stryker gasped that he didn't know it was him then and he tried to warn him. Wolverine released him and told him that after he kills Sabertooth he will be coming back for him. Stryker tells him that he has the tools to defeat Sabertooth and offers Wolverine the tools. Wolverine accepts the offer, but not knowing what the tools were. It turned out to be the Adamantium. Stryker said he found the Adamantium just after he left the team.
Stryker informs Wolverine that it has to be inserted in his body, covering his entire skeleton, including the one-foot bone claws that come out of his knuckles. But he warns it will be the most painful thing he will ever have encountered. He also tells him once he has the adamantium, he will be indestructable. They start the operation on Wolverine and finish it. But just as the operation finished, Stryker orders a memory wipe. Wolverine overhears and escapes the operation lab, furious Stryker tricked him.
Stryker sends Agent Zero, one of the three former Team X members that is still with Stryker, to find and kill Wolverine. A day later, Agent Zero reports to Stryker that he found Wolverine in a farm with two farmers looking after him, and just killed the two farmers. Then Wolverine chases Agent Zero in a motorbike and kills him, just after he told Stryker that he is still on to him.
Two days later, Wolverine comes to Stryker's secret base on the Three-Mile Island, telling him he just found out about the mutants he captured and kept on the island. A mutant called Gambit (who can charge objects up and explode them), one of the mutants that had been captured, but escaped, had helped Wolverine come to the island.
So after Wolverine entered Stryker's secret base on the island, Stryker reveals that he and Sabertooth, the second former Team X member that was still with Stryker, had been working with Wolverine's wife all along. He tells Wolverine that his wife had been a spy for him and that his wife was in fact alive now. Sabertooth had "attacked" Wolverine's wife but had not actually killed her. He put fake blood on her and inserted a drug in her body that reduces her heartbeat so slow it seems that she is dead. The whole thing was an act. Stryker also reveals that she is also a mutant with powers of persuasion as long as she's touching them. Then Wolverine's wife, who was in the building all along, entered.
Wolverine, furious, leaves the building, just after he hears his wife scream. He runs back to the Stryker's secret base and sees Sabertooth strangling his wife, wanting the Adamantium Stryker just refused him. Sabertooth lets go of her and he and Wolverine start fighting. Wolverine wins the fight, thanks to his new, indestructable Adamantium claws, but doesn't kill him, remembering his humanity, and instead, knocks him unconscious.
Then his wife tells him that they should free all the mutants captured in Stryker's secret base. They succeed and head for the exit, but then Deadpool, the last former Team X member that was still with Stryker, stops them. Stryker was controlling Deadpool with a computer, thanks to the microchip he had just inserted in Deadpool's brain, and commanded him to kill Wolverine. The DNA that Stryker told Sabertooth to collect was actually for Deadpool, who now had all the powers of the captured mutants. Deadpool had swords coming out of his knuckles, teleport powers, healing powers and optic blasting from his eyes (DNA from a mutant called Scott Summers/Cyclops).
Wolverine tells his wife and the mutants they just freed to find another exit while he would take care of Deadpool, ready for a fight. They do and Wolverine lures Deadpool to the top of a nuclear plant. They start fighting but Wolverine almost dies when he was about to fall in the nuclear plant when he was saved by Sabertooth, who was also tricked by Stryker. They decide to team up against Deadpool and they defeat him by chopping his head off and kicking him into the nuclear plant.
Sabertooth then runs off to nowhere and Wolverine and Gambit reunite. It turned out Gambit stayed at the island for no reason and was watching the fight. Then Wolverine sees his wife injured. She had been injured when Sabertooth strangled her with his sharp claws. She was dying when Wolverine was shot with an Adamantium bullet by Stryker. Too much Adamantium in your body can cause memory loss. So while Wolverine was healing slowly, Stryker was about to shoot Wolverine's wife when she suddenly touched his foot and told him to drop the gun and go away. So he did and she died.
When Wolverine fully healed from the Adamantium bullet, he found that he lost his memory. Gambit then goes up to Wolverine and Wolverine asks him what his name is, who is he and where is he. Gambit, confused, just goes separate ways from Wolverine and they just wonder off.
Soon afterwards, Stryker is arrested for a murder he did a few days earlier and goes to jail.
At the end of the movie, Wolverine is seen drinking at a bar at Japan, trying to find his history.