Crossover Events
Major X-Men crossover events with core vs. optional issue breakdowns.
Dark Phoenix Saga
Jean Grey's transformation into the all-powerful Dark Phoenix threatens the entire universe, forcing the X-Men to confront one of their own. After consuming a star and destroying a populated planet, the Shi'ar Empire demands Jean's death, leading to a trial by combat on the Blue Area of the Moon that ends in devastating sacrifice.
Days of Future Past
In a dystopian future where Sentinels have conquered North America and most mutants are dead or imprisoned, an adult Kate Pryde sends her consciousness back in time to her younger self to prevent the assassination of Senator Robert Kelly. This two-issue storyline established the X-Men's most iconic alternate future and raised the stakes of the mutant-human conflict.
Mutant Massacre
The Marauders, led by Mr. Sinister, slaughter the Morlocks in the tunnels beneath New York City. Multiple X-teams are drawn into the conflict with devastating consequences. Angel's wings are destroyed, Colossus is critically injured, and the X-Men and X-Factor clash before discovering they're on the same side.
Fall of the Mutants
Three separate but simultaneous storylines reshape the X-Men landscape. In Dallas, the X-Men sacrifice their lives to stop the Adversary and are secretly resurrected by Roma. In New York, X-Factor battles Apocalypse and his Horsemen, including the transformed Angel as Death. The New Mutants face their own deadly threat as the Bird-Boy storyline reaches its tragic conclusion.
Inferno
Madelyne Pryor is revealed as a clone of Jean Grey created by Mr. Sinister, and she transforms into the Goblin Queen, opening a demonic portal over New York City. As demons overrun Manhattan and inanimate objects come to life, the X-Men and X-Factor must confront Sinister's manipulations, Illyana Rasputin's ties to Limbo, and the truth about Madelyne's origins. The event resolves long-simmering plotlines and permanently alters the X-Men's status quo.
X-Tinction Agenda
The island nation of Genosha kidnaps members of the X-Men and New Mutants to enslave them using the mutate bonding process. The combined forces of the X-Men, X-Factor, and New Mutants launch a rescue mission that topples the Genoshan government. Cameron Hodge, now a monstrous cyborg, serves as the primary antagonist, and Havok is brainwashed into serving Genosha as a magistrate.
X-Cutioner's Song
When Cable appears to assassinate Professor X at a mutant rights rally, the X-Men and X-Factor hunt him down, only to discover that the true culprit is Stryfe, Cable's clone from the future. As Xavier lies dying from a techno-organic virus, the teams must confront Stryfe, Apocalypse, and the dark legacy of the Summers bloodline. The event deepens the mystery of Cable's origins and introduces the Legacy Virus that will plague mutantkind for years.
Age of Apocalypse
When Legion travels back in time to kill Magneto but accidentally murders Professor X instead, reality is rewritten into a world where Apocalypse conquered North America unchallenged. For four months every X-book was replaced by an alternate-reality counterpart. Magneto leads the X-Men in Xavier's memory, fighting to restore the original timeline before the Human High Council launches a nuclear strike to stop Apocalypse.