Every X-Men character has a unique power and personality, but it's that stark individuality that makes them outcasts in the Marvel universe. Their shared conundrum of feeling ostracized for the very thing that makes them special is the engine that powers the most compelling family of books in Marvel's cannon.
The books follow intricate, layered story lines that are essential reading for any super hero enthusiast. It could be argued that even though Spider-Man may have introduced the art of lengthy and powerful story lines, X-Men books perfected it with some of the best arcs in comic history.
Sadly, not every issue is great. Some of them are awful, or worse, inconsequential. If you don't have the time to read literally infinite comic books, here are the most essential X-Men story lines to get you caught up.
The Dark Phoenix Saga
Story Found In: The X-Men #129-138
At the height of his powers, writer Chris Claremont cast long-time protagonist Jean Grey as the X-Men's greatest foe when the sheer burden of her powers and a nudge from Mastermind (a villainous mutant with the ability to cast illusions) push her to abandon morality and embrace the world-breaking telekinetic potential of the Phoenix Force. It's a cosmic opera in which Jean kills millions, faces a trial at the hands of the alien Shi'ar race, and ultimately sacrifices herself for the good of the galaxy.The drama lies not only in Jean's struggle, but in the anguish of her friends and teammates as they watch her descent into madness. Professor X watches his most powerful student spiral out of control while Cyclops watches the love of his life unravel. The Dark Phoenix Saga is not only one of the greatest X-Men tales, but it is also a frequent nominee for the best comic book storyline of all-time.
Days of Future Past
Story Found In: The Uncanny X-Men #141-142
"Days of Future Past" is the first alternate timeline storyline in the X-Men books and a short, succinct, and airtight one at that.
In a dystopic future, mutant hunting Sentinel robots have eradicated mutants and turned their murderous intentions to normal humans. Kitty Pryde and the remaining X-Men use her mutant ability to phase her mind through time (instead of Wolverine like in the 2014 film version) to save an arrogant, mutant hating Senator whose death would have lead to that unhappy future.It posits the idea that one person's life or death can drastically change everyone's future, three years before The Terminator and introduces an alternate timeline without the messy crossover that later alternate timeline stories would indulge.
The Phoenix Saga
Story Found In: The X-Men #101-108
Before there could be "The Dark Phoenix Saga," there had to be "The Phoenix Saga." When the X-Men's lives are threatened by radiation on a trip home from outer space, Jean transforms from her mild-mannered Marvel Girl persona to become the Phoenix, an angry force of nature that manifests a fiery bird to do her telekinetic bidding and that has the potential to destroy planets.The relationship between Jean and the Phoenix becomes very confused in later stories, but in this original telling, we believe that Jean is still Jean and see her achieving the full potential of her mutant powers to save the universe from the near collapse of the M'Kraan Crystal.
Age of Apocalypse
Story Found In: Uncanny X-Men #320–321, X-Men Vol. 2 #40–41, Cable #20, X-Men Alpha, Amazing X-Men #1–4, Astonishing X-Men Vol. 1 #1–4, Factor X #1–4, Gambit And The X-Ternals #1–4,Generation Next #1–4, Weapon X Vol. 1 #1–4, X-Calibre #1–4, X-Man #1–4, X-Men Omega, Age of Apocalypse: The Chosen and X-Men Ashcan #2
While "Days of Future Past" is a succinct alternate timeline story, "Age of Apocalypse" is not. When Professor Xavier's son, a schizophrenic mutant named Legion, goes back in time to kill Magneto but accidentally kills his father, a new timeline is created where the omni-powerful villain, Apocalypse, has assumed tyrannical control of the Earth.The X-Men manage to unravel his empire, but the strength of "Age of Apocalypse" was that it let a superstar team of creators led by Scott Lobdell present new versions of every single X-Men character. The powers are the same, but the unique costumes, attitudes, and allegiances are the stars of this storyline.