X2 (promoted in some markets as X2: X-Men United, X-Men 2: X-Men United, or X-Men 2) is an American movie, first released in the United Kingdom on April 24, 2003, and in the United States on May 2. The film is second in the trilogy; following X-Men, and preceding X3. It was directed by Bryan Singer, and starred an ensemble cast including Patrick Stewart, Hugh Jackman, Ian McKellen, Halle Berry, Famke Janssen, Anna Paquin, Brian Cox, and Alan Cumming.

The film is loosely based on the 1982 X-Men graphic novel God Loves, Man Kills. In the film, William Stryker is a high-ranking army colonel who leads an assault into Professor Xavier's school to build his own version of Xavier's mutant-tracking computer Cerebro in order to destroy every mutant on Earth. The X-Men are forced to ally with Magneto and Mystique to defeat Stryker. X2 introduced Nightcrawler to film-goers, and was an even greater success than the original film, earning approx. $215 million in North America alone, making it one of the top ten movies of 2003. It was also proclaimed by many fans and critics a superior film than its predecessor.

The opening scene shows a mutant by the name of Nightcrawler attempting an assassination of the President of the United States. He is stopped at the last moment after being shot, he does however drop his weapon before disappearing - a knife that reads "Mutant Freedom!".

Wolverine finally reaches Alkali Lake, the facility used for experiments on mutants like him. He finds nothing but an empty dam. Meanwhile, the mutants of "Professor Xavier's School for the Gifted" visit a museum. Jean Grey is confronted by Cyclops after she demonstrates her lack of focus. She confesses to him that she has been having bad feelings about the future. During their conversation, Iceman and Pyro are in the cafeteria. After a scuffle between them and another young man, (in which Pyro manages to set alight the young man's clothes) the entire world slows down, people stop and stare off into space. The mutants are, however, not affected. Professor Xavier wheels in, unamused by the situation, and decides that it is time to leave. As the world begins to move again, the boy realizes that Pyro and Iceman are gone.

Wolverine reappears at the School for the Gifted and is immediately forced to "babysit" the children of the school. Storm and Jean attempt to locate Nightcrawler while Cyclops and Professor X visit Magneto in his plastic prison. Storm and Jean easily find Nightcrawler held up in a church and take him into the X jet to take him to the School. Meanwhile, during their visit to Magneto, Cyclops and Professor X are captured.

Wolverine awakens to nightmares of his first memories and heads to the kitchen. While conversing with Iceman, a military invasion of the school begins. The soldiers attempt to sedate every mutant they find; however, many of the children escape with the help of Wolverine. He stays behind though, to confront the attacker, William Stryker. Stryker reveals that he knows much about Wolverine and wishes for him to come with the military to discuss it. Before Wolverine answers, Iceman is able to create an impenetrable wall of ice between them. The kids persuade Wolverine to come with them, to protect them.

Wolverine and the kids (Pyro, Iceman, and Rogue) head to Iceman's home in Boston. After an awkward meeting between his parents and Wolverine, Iceman decides to tell his parents (who believe he has been going to a boarding school) that he is a mutant. While the group discusses it, Iceman's disgruntled brother runs upstairs. While above them, he calls the police, saying that the group would not let him or his parents leave the house. Wolverine meanwhile receives a call from Storm who decides to come and pick them up, just as the police arrive.

During the standoff, a police officer mistakes Wolverine's claws for knives and orders him to drop them. When Wolverine tries to explain by sheathing his claws, the officer shoots Wolverine in the head. After this, Pyro becomes enraged and begins using his powers to destroy the police cars and blow away the officers. Just as his rage reaches a high, Rogue touches him in order to stop his rampage. Pyro falls to the ground, drained of his energy and power as the X jet arrives to pick them up.

While flying through the sky the X jet is targeted by military aircraft who attempt to force a landing. After the X jet refuses to land, the jets fire on it. Storm creates a number of tornados in order lose the aircraft. One plane is unable to maintain control and ejects. The other is able to fire two missiles before ejecting. Storm attempts evasive maneuvers, but quickly loses distance. Jean uses her powers to an unnaturally high level and is able to destroy one of the missiles. Unfortunately the other hits the jet, rupturing the fuselage. In the ensuing depressurization, Rogue is pulled out of her seat and out into a free fall. Nightcrawler teleports outside the jet to grab Rogue, then teleports back in, saving her life. The jet, still enroute to a crash landing, is stopped at the last moment by Magneto on the ground.

Magneto has learned that Stryker orchestrated the attack on the President in order to gain approval to attack the school and has been experimenting on mutants at Alkali Lake. When Wolverine claims that there is nothing at Alkali Lake, Magneto refutes that the base is inside the dam. Stryker is able to control mutants with a powerful drug that he has used on Nightcrawler, Magneto and a number of other mutants - and he has also built a new Cerebro and plans to use Professor X to kill all mutants in the world. The X-Men and Magneto join together to stop Stryker.

Stryker gains control over Professor Xavier through his son, Jason (a former student of the professor), who is able to project powerful visions in the mind, blinding a person to reality. Jason (in the form of a young girl) instructs Professor X to use Cerebro to find all existing mutants and kill them. While the X-men and Magneto stage their attack, explosions cause cracks in the dam that will lead to the destruction of the base. Wolverine runs off on his own to find Stryker. He does so along with Lady Deathstrike. After Stryker leaves, Wolverine attempts to follow him but is stopped by Deathstrike. A battle of blades begins between the two which eventually results in Wolverine pumping Deathstrike full of adamantium metal, instantly hardening her body. Wolverine finds Stryker on a landing pad, stabbing him in the stomach. Stryker attempts to bargain with Wolverine, telling him that if he comes with him he can tell him about his past. Wolverine refuses and straps the wounded Stryker to the helicopter wheel saying that if the X-men die, Stryker will too.

Magneto breaks into the new Cerebro with Mystique and convinces Jason to tell Professor X of a "change of plans" - to kill all humans. Magneto escapes on the helicopter, taking Pyro along with him. The X-Men save Professor X and stop the killing process but the dam is falling apart. As the team prepare to leave, Wolverine revisits Stryker and gets rid of his mutant tag. The X jet will not rise and the whole dam falls apart. The flood gets stronger, drowning Stryker. Jean Grey leaves the jet, uses her powers to stop the onrushing flood, and raises the jet at the same time. Nightcrawler attempts to grab her but she refuses to allow him to. She raises the jet high enough and the water floods over her. Cyclops and Wolverine mutually mourn the loss.

Back in the White House, the President prepares to address the country. When he is about to begin the lights flicker and the room freezes in time, except the President. The X-Men appear before him and Professor X tells him about the events of the last few days, saying that there have been casualities on both sides. And that he must come to a decision: Either the humans and mutants work together to build peace, or destroy each other through war. They leave in the same manner they entered. The President, shocked, prepares to continue his speech.

The film ends with a voice-over by Jean Grey, similar to the voice-over from the original film, on the process of evolution as the camera floats over Alkali Lake, showing a vague but ominous shape (clearly a phoenix) in the water surface.

The basic story elements, involving Stryker's plot to use Xavier's powers against all mutants, and the X-Men's resulting alliance with Magneto, are loosely adapted from the graphic novel God Loves, Man Kills by Chris Claremont. In that story, Stryker has a military background, but is currently a religious leader whose wife gave birth to an obviously mutant infant. In a fit of rage, he killed them both and decided that he had been chosen by God to destroy mutants. In the film, his military background is moved to the foreground, and the religious aspect of the character is eliminated. Instead of killing his wife and son in childbirth, the Stryker of the film sends his son (loosely based on the character Mastermind from the comics) to Xavier to be cured of his mutation. Unable to change his mutation, and resentful of his parents, he began tormenting his mother by projecting nightmarish images into her brain, causing her to commit suicide by drilling a hole into her head. Stryker responded by giving his son a lobotomy, and extracting his brain fluid, which he now uses to control other mutants.

In the scene where Mystique accesses Stryker's computer for the location of Magneto's cell, a list of mutants can be seen, many of which are from the comic books, including Remy LeBeau (Gambit), the Guthrie children Sam (Cannonball) and Paige (Husk), Kevin McTaggert (Proteus, the son of Moira MacTaggert), Jamie Madrox (Multiple Man), the Maximoff children Wanda (Scarlet Witch) and Pietro (Quicksilver) - both of whom are Magneto's offspring - Xi'an Coy Mahn (Karma), and Danielle Moonstar (Moonstar); the latter two are part of the New Mutants group of the X-Men. Also seen on the list was Arthur Maddicks, a Morlock in the comics; it is generally assumed that the child with the forked tongue, called 'Artie' by Storm is Arthur Maddicks in the film's universe. At first, a rubber tongue was used for this scene but it was taken by someone right before the last scene and for the last scene showing the tongue, a CGI tongue was inserted.

In the very same scene, where Mystique glances over at the other monitor and sees plans for Cerebro, other files on Stryker's computer include: a folder on Franklin Richards, the reality-altering son of Reed and Susan Richards of the Fantastic Four; a folder on Omega Red; a folder on Project Wideawake, an operation that called for the construction of giant, mutant-hunting robots known as Sentinels; and a folder on Muir Island.

In the scene where Mystique confronts the guard to Magneto's plastic cell in a bar, the news is on the TV by the bar. On the news is an interview with a so-called "Dr. Hank McCoy", who in the comics is the member of the X-Men known as Beast, debating Dr. Sebastian Shaw, who is the Black King of the Hellfire Club.

In the scene where William Stryker's thugs raid Charles Xaiver's school for mutants, students running from the thugs include Kitty Pryde and Theresa Rourke Cassidy. Theresa is the girl who screams the blood-curdling scream which wakes everyone up, and Kitty is the girl who becomes intangible, falls through the bed and jumps through several guards.

In the lab where Wolverine got his adamantium skeleton, there are x-rays on the wall. One of the x-rays looks like a person's back with a wing. This may be referencing where in the comics the X-man Angel lost his wings and later got metal ones. There are also X-rays of one of Deathstrike's forearms and hands, with her talons retracted and extended.

A bit more obvious amount of foreshadowing of the third movie is used. Whenever Jean's powers became stronger than usual, she was often depicted as glowing with fire, a sign of the Phoenix. The ending shot over the Alkali Lake shows the image of a burning object in the shape of a bird under the water.

Longtime fans of the X-Men title will recognize that some liberties have been taken with the X-Men characters. While the movie need not follow all the conventions of the comic, they are interesting to note and may be considered to be parallels with the Ultimate X-Men series.

Iceman appears as a teenager and appears much younger than many of the other X-Men. In the comics, Iceman was one of the original X-Men. He appeared and left many years before the 1980s X-Men like Rogue, Storm, and Wolverine. If he were around at all, he would appear closer to Jean Grey's age and maturity. Iceman and Jean Grey and Cyclops are part of the original X-Men line-up.
Colossus is in this movie but has only a very small part and is not part of the X-Men team, only an older student of the academy. While young in age when he began with the X-Men, he was a full-fledged member for many years in the comics. In addition, he does not speak with the expected Russian accent.
William Stryker is a zealot preacher in the comics, while the film's version is the head commander of the covert black ops program Weapon X. His son, Jason, is a very loose incarnation of Jason "Mastermind" Wyngarde, who was a full-grown, mentally and physically able illusionist (with no relation to Stryker) from the Brotherhood of Evil Mutants and Hellfire Club in the comics. In the film, Jason is mute, lobotomized, and wheelchair-bound; his brain secretes a powerful chemical which is extracted through a tap in his spine and used by his father as a mind control agent on Deathstrike, Magneto, and Cyclops. In his illusions, Jason projects himself as a teenage girl; both he and his illusory form have mismatched eyes (one blue, one green).
Deathstrike, who in the movie appeared as a mutant under Stryker's control was once Wolverine's love interest in the comic books. Also, in the comics she was a cyborg, not a mutant.
Rogue, according to the comic books has the ability of flight and superhuman strength, whereas in the movie she lacks these abilities. However Rogue only possesses these abilities in the comic books because she accidentally absorbed Ms. Marvel's powers by touching her for too long. By changing her backstory, skipping her original villainous phase, she is closer to her original basic ability.
Rogue, in the comic books has origins in the south, and also a distinct southern accent. This is another alteration that fans may have been aware of. It may also be noted that in the 90's series of the comics famed cartoon adaptation, Rogue and Wolverine often got into disputes. She wasn't emotionally attached to him, as the movie depicts.
Magneto and Professor X are American (Magneto being a Polish immigrant), but both are shown in the movie as having British accents.
There is no indication in the movie that Mystique is Nightcrawler's mother. Neither is there any indication in the movie that Mystique is Rogue's foster mother. However, as in the comic book, Mystique and Nightcrawler bear a strong physical resemblance.
In the movie Pyro is shown to be an American teenage student working with the X-Men, in the comics he is an Australian writer in his 40s that always worked with the Brotherhood
Jean Grey can levitate in the comics, but in the movies, she is never depicted as having that talent. This especially plays into the ending, as Jean could have lifted herself up in the air while holding back the torrents of water.
In summary, characters from many different times, titles and lineups are cherry-picked and placed into a new lineup never before seen in any X-Men comic or graphic novel.

Just as the original film had done, X2 garnered high praise from critics and won over most of the comic book community, who regarded it as a vast improvement over the original, and it went on to make even more money at the box office than its predecessor. Some fans, however, continue to feel annoyed at Wolverine's prominence while the other X-Men, particularly Cyclops, are relegated to second string status. Wizard magazine stated it as the best comic book movie at that time of the issue was released (2003).