X-Tinction Agenda
"X-Tinction Agenda" is a 1990 crossover comic book storyline published by Marvel Comics that ran through Uncanny X-Men and its spin-off titles, X-Factor and New Mutants. "X-Tinction Agenda" not only reunited the X-Men after a prolonged period in which the team had been scattered around the globe (following the events of Uncanny X-Men #246-251), but featured the combined might of the three mutant teams for the first time, in their fight against the mutant-exploiting Genoshan government.

Plot
Genoshan magistrates, backed by the cyborg Cameron Hodge, and including an amnesiac Havok (a member of the X-Men), attack the X-Mansion and kidnap Storm and the New Mutants Warlock, Boom Boom, Rictor, and Wolfsbane. After expending his energy on freeing the others from their cell, Warlock is taken to have his power transferred to Hodge. Wolfsbane returns to rescue him, but instead unintentionally causes the transfer to go awry, killing Warlock. Wolfsbane is brainwashed, turned into one of Genosha's mindless mutate slaves, which form the backbone of the Genoshan economy and lifestyle. The remaining New Mutants and the X-Men recruit X-Factor and head to Genosha to save their teammates, only to be ambushed by Havok and the Genoshan magistrates. As Cyclops unsuccessfully attempts to jog Havok's memory, the Genoshans meet a humiliating defeat.

Wolverine, Psylocke, and Jubilee rescue Rictor and Boom-Boom from Genoshan magistrates. After entrusting Rictor and Boom Boom to the care of Jubilee, Psylocke and Wolverine put on the magistrates' uniforms to enter Hammer Bay. Havok, seeing someone else is wearing his lover's uniform, attacks his former teammates. Psylocke incapacitates Havok, but Hodge takes her and Wolverine prisoner. Meanwhile, Storm attempts to kill Genoshan engineer David Moreau, but is captured by Hodge and turned into a mutate slave. Jean, Cable, Gambit, Sunspot, and Forge place bombs throughout the outer levels of the capitol building, the Citadel, but are captured after the magistrate Wipeout blocks their powers. The remaining heroes set a trap at their hideout and attack the Citadel, but are defeated. Wanting payback for his earlier humiliation, Havok confronts Cyclops personally. This time Cyclops succeeds in making Havok remember who he is. However, deciding his only chance of helping is as an inside man, Havok tranquilizes Cyclops and turns him over to Hodge.

The X-Men, X-Factor, and New Mutants are put on trial, but when Wolverine attempts to kill the judge, he turns them over to Hodge to do with as he will. Pretending to be traumatized by Hodge's brutalities, Psylocke submits herself to the mutate process. She then escapes while being taken to Moreau. Once the others are left alone, Gambit uses a dart Hodge fired into his leg to pick their locks. Thinking the mutants are all safely captured, Hodge initiates his plan to betray Genosha, killing a number of magistrates, including Wipeout. The Chief Magistrate turns to the mutant teams for help against Hodge, using Storm's electrical power to restore their powers. The process inexplicably also undoes Storm's brainwashing and restores her to adulthood. 

Jubilee, Rictor, and Boom-Boom stumble upon Moreau, who is taking his own steps to counter Hodge's treachery. He takes them to the Citadel. There, they are reunited with their teammates. Moreau directs Wolfsbane to change into wolf form; only by remaining in this form can she be free of her brainwashing. Moreau shoots Hodge point blank with a prototype weapon, but Hodge kills him before he can finish him off. The mutant teams hunt Hodge throughout the Citadel, with Cyclops and Havok finally destroying his body. Hodge's severed head still lives on due to the immortality bestowed on him by N'Astirh, so Rictor brings down the Citadel, burying him alive. Days later, Havok and Wolfsbane decide to stay in Genosha to help settle tensions between humans and mutants in the country. The mutant heroes return home and hold a funeral for Warlock. Per Wolfsbane's wishes, they spread his ashes over the grave of their teammate Cypher.

Impact
Published during the comic book speculator boom, the involvement of Jim Lee and Rob Liefeld caused the issues of the crossover to sell for $10–20 on the secondary market when the books were first published, though the issues have since gone down in value.

The storyline also had several lasting effects on the various titles.

The loss of longtime New Mutants members Wolfsbane, Rictor and Warlock would begin the book's transition to X-Force.
The various X-Men in the story (Storm, Wolverine, Banshee, Forge, Psylocke, Jubilee, Gambit) would form the first official X-Men roster since the Australia-based team disbanded.
The mutate process would psychically bind Wolfsbane to Havok - a plot thread that would be picked up after both joined X-Factor.

Continuity errors
Apparently due to not being in agreement over what exactly should be depicted in the scenes drawn by their respective artists or maybe because of them not being aware of what the others had drawn, the parts drawn by Bogdanove differ greatly from what Lee and Liefeld depicted.

 In the parts drawn by Liefeld and Lee, Forge has lost his bionic arm and leg; Bogdanove drew Forge with his bionic limbs still firmly intact.
 Wipeout, in the parts drawn by Liefeld and Lee, is a short man with spiky gray hair and wearing a pair of round glasses. In the parts of Bogdanove he's long haired, has a moustache and lacks the glasses. 
 In the parts drawn by Liefeld and Lee Wolverine is wearing his orange and brown suit, in the parts drawn by Bogdanove he's "Patch" wearing a plaid jacket and jeans.
 When a tearful Wolfsbane gives Warlock's ashes to Boom-Boom in the scene drawn by Liefeld, she's wearing her Genosha slave outfit and has a humanoid appearance, in the Bogdanove drawn reprise of that scene she's drawn completely wolf-like wearing torn rags.

Secret Wars (2015)
The Secret Wars storyline features a new "X-Tinction Agenda" miniseries that is part of the event.

Ten years since the Summers brothers took out Cameron Hodge and end his fascist regime in Genosha, Havok and Wolfsbane have toiled and labored to rebuild the island into the proud mutant homeland it once was. But a decade removed from Hodge and his iron rule, their work may all be for naught. A plague has spread across the nation, infecting mutants and threatening the domain known as X-Topia. Faced with an extinction problem, Baroness Rachel Grey had no other solution than to quarantine the island from the rest of the domain, leaving Havok in charge. With the country quarantined and seemingly abandoned by their God and the rest of their fellows X-Men, Havok and Wolfsbane will stop at nothing to save those who are currently trapped on Genosha.

While walking around X-City, Rachel Grey is discussing with Beast about the experiment he is currently developing, more precisely where Beast had time-transplanted some X-Men. In this case, Banshee, Thunderbird and Wolverine just to prove the concept that its possible to bring the dead back to live by taking them from the time before they died. Just then, they are attacked by Havok and his Press Gang in an attempt to capture the mutant healer Triage, the last ray of hope for the mutants of Genosha. The battle is fast and fierce, pitting mutant against mutant, and showing that Havok is taking no chances in reaching his end goal. When Triage is found, Havok pulls the team back to Genosha taking former friends as prisoners along the way. Tests are set up to ensure that Triage's powers will work against the virus. Seeing this as an act of treachery, Rachel Grey prepared to wage war on Genosha.

Baroness Grey gathered a small group of mutants to invade Genosha in order to save the kidnapped X-Men and punish Havok and his allies for their attack. Unbeknownst to them, Dr. Aldus Kluge (known as the Genegineer) didn't want Triage's power to stop the virus, but to resurrect Cameron Hodge so he could continue his mission to eradicate mutantkind. Upon Hodge's resurrection, Kluge revealed to him that he was the one responsible for creating and spreading the Extinction Virus and that his ultimate goal was to resurrect Hodge and merge him with an Adamantium Exoskeleton and the Transmode Virus (which he acquired from the remains of Warlock) so he could purge Genosha from its mutant population. As Triage and Rogue were curing the mutant population of Genosha from the virus, Baroness Rachel Grey launched an attack on the island nation. During the battle, Wolfsbane was launched in the air by Storm and Bulletproof was forced to flee from his battle against Thunderbird to save her, ending up crashing into Kluge's lab and discovering what he had done and what he was up to. Afterwards, Bulletproof was attacked by Ink and accidentally merged with part of the Transmode Virus, then proceeding to kill Kluge for his betrayal. With Kluge dead, the X-Men had a new problem at hand....a fully resurrected Cameron Hodge merged with what remained of the Transmode Virus.

With the threat of Hodge growing as he learned how to use his newfound powers, both the X-Men of Genosha and X-City called a truce and allied themselves to fight him. However, Hodge was too powerful to be defeated by their combined effort. Wolfsbane then devised a plan to stop him and used Mystique as a distraction to buy her enough time to get to their airplane along with Havok and Bombshell. With their powers combined, Havok and Bombshell exploded Genosha as Wolfsbane crashlanded into Hodge, leaving no trace of them behind. Having survived the explosion along with the X-Men of Genosha and X-City which she protected using her powers, Baroness Grey vowed to rebuild Genosha in honor to the mutants who died defending it and to unite it with X-City, as it was meant to be from the beginning. Meanwhile, what little remained of Warlock rose from the island's ruins and brought Warlock back to life.

Publication
Uncanny X-Men #270 (November 1990)
New Mutants #95 (November 1990)
X-Factor #60 (November 1990)
Uncanny X-Men #271 (December 1990)
New Mutants #96 (December 1990)
X-Factor #61 (December 1990)
Uncanny X-Men #272 (January 1991)
New Mutants #97 (January 1991)
X-Factor #62 (January 1991)

Collected editions
The storyline has been collected into a trade paperback:

X-Men: X-Tinction Agenda (224 pages, September 17, 2001, )
Collects Uncanny X-Men #270-272; New Mutants (1983) #95-97; X-Factor (1986) #60-62

It has also been collected into a hardcover:

X-Men: X-Tinction Agenda (304 pages, August 10, 2011, ) 
Collects Uncanny X-Men #235-238, #270-272; New Mutants (1983) #95-97; X-Factor (1986) #60-62