WARNING: The following article contains minor spoilers for Uncanny X-Men #7 by Matthew Rosenberg, Kelly Thompson, Ed Brisson, Pere Perez, Rachelle Rosenberg and Joe Caramagna, on sale now.

In the Age of Apocalypse, the X-Men's worst nightmares are a reality. Over 20 years after it was first published, this fan-favorite storyline still stands as one of the X-Men's most truly epic tales. After Xavier's all-powerful son Legion traveled back in time and accidentally killed his father before he formed the X-Men, the X-villain Apocalypse took over the world and reshaped it in his own twisted image of mutant supremacy.

Led by Magneto, a ragtag team of X-Men was finally able to topple Apocalypse's regime and restore the proper timeline, seemingly destroying the Age of Apocalypse timeline in the process.

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After taking over the X-Men's world (and publishing line) for four months in 1995, the Age of Apocalypse was over. But nothing ever really ends in the Marvel Universe, and it wasn't long before that alternate reality started popping up again.

Now, CBR is taking a look back at all of the times Marvel returned to the Age of Apocalypse after the original storyline ended. From early one-off stories to the ongoing Uncanny X-Men storyline "X-Men: Disassembled," this dystopian world has lived long past its planned ending and evolved into one of the most distinct worlds in Marvel's multiverse.

X-MAN AND THE EXILES

X-Man Exiles

When the Age of Apocalypse seemingly vanished in a burst of energy, a handful of that world's residents escaped into the main Marvel Universe. The most prominent of these refugees was the ultra-powerful Nate Grey, the Age of Apocalypse's version of Cable. Long before he became the would-be mutant savior who's been causing problems in Uncanny X-Men, Grey explored and protected the Marvel Universe in X-Man, which ran from 1995 until 2001.

Over the course of X-Man's 75-issue run, Nate had occasional flashbacks to his time in Apocalypse's world. X-Man also fought Dark Beast and Sugar Man, two monstrous mad scientists from the Age of Apocalypse who caused trouble for years in the main Marvel Universe.

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Another one of the Age of Apocalypse's breakout stars, the purple-skinned teleporter Blink, began carrying on her world's legacy around the time X-Man ended.

In Scott Lobdell, Judd Winick and Trevor McCarthy's Blink, Blink found herself in the Age of Apocalypse's version of the extra-dimensional Negative Zone in 2001. That miniseries led directly into Exiles, where Blink led an ever-changing team of X-Men from other dimensions as they traveled through Marvel's multitude of alternate realities, fixing Marvel's overall timeline as they went along.

While Blink wasn't always a member of the team, she was one of Exiles' main leads for its 100-issue run and returned to that role in the recently-canceled Exiles. During her Quantum Leap-esque adventures with that team, she returned to the Age of Apocalypse and encountered a few of its residents, including her mentor Sabretooth and Apocalypse's son, Holocaust.

TALES FROM THE AGE OF APOCALYPSE

X-Men Tales Age of Apocalypse

After the "Age of Apocalypse" crossover ended in June 1995, Marvel made its first return trip to a slightly different version of the Age of Apocalypse a few months later in What If? #81, by Mariano Nicieza and Kevin Hopgood. In "What If the Age of Apocalypse Had Not Ended?," the unlikely team of Magneto, Iron Man and Night Thrasher keep Galactus from consuming their world.

In 1996 and 1997, Marvel produced Tales from the Age of Apocalypse, a pair of one-shot prequel specials that looked at the earlier days of the Age of Apocalypse.

Blink was the focus of Scott Lobdell, Ralph Macchio and Joe Bennett's Tales from the Age of Apocalypse #1, which showed how a heroic Sabretooth brought the teleporter to the X-Men. In Tales from the Age of Apocalypse #2, John Francis Moore, Brian K. Vaughan, Steve Epting and Nick Napolitano explored the cosmic side of the Age of Apocalypse while filling in the histories of the world's villainous Cyclops and Havok.

NEXT PAGE: The Age of Apocalypse Let the Dark Angel Saga Take Flight

THE NEW AGE OF APOCALYPSE

X-Men Age of Apocalypse anniversary

To celebrate the 10th anniversary of the "Age of Apocalypse," Marvel made its first full return to that dark alternate reality in 2005 with a one-shot special and the miniseries X-Men: Age of Apocalypse, by C.B. Cebulski and Chris Bachalo.

Thanks to the sudden emergence of Phoenix-level powers, Jean Grey was able to save the Age of Apocalypse from total annihilation, and that world's X-Men helped build and maintain a fragile peace. While the series featured the return of Age of Apocalypse characters like Weapon X and Magneto, it also marked the debut of characters like X-23, Silver Samurai and Psylocke, who weren't part of the original crossover.

While this story wasn't terribly well-received, it was instrumental in establishing the Age of Apocalypse as an active part of Marvel's wider multiverse of alternate worlds and setting the stage for one of the most well-received X-Men stories in recent memory.

THE DARK ANGEL SAGA

Uncanny X-Force Dark Angel Saga

Starting in 2011's Uncanny X-Force #11, Rick Remender and Mark Brooks kicked off "The Dark Angel Saga," a return to the Age of Apocalypse that easily stands as one of the best X-Men stories of the decade. With art from Jerome Opena, Scott Eaton and Esad Ribic, the story sees Wolverine's X-Force team travel to the Age of Apocalypse to obtain a Life Seed that can keep Archangel from turning into a new Apocalypse.

The ensuing story saw Weapon X, the Age of Apocalypse's Wolverine, take over that world as the vicious Heir to Apocalypse. After the Age of Apocalypse's Iceman betrayed the X-Men and fled to the Marvel Universe, the Age of Apocalypse's Nightcrawler joined X-Force to hunt him down.

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Following that story, Marvel launched a short-lived ongoing series called Age of Apocalypse in 2012. Created by David Lapham and Roberto De La Torre, that series followed the Age of Apocalypse's Jean Grey and a team of human fighters. That series ended with Jean Grey assuming Apocalypse's powers and leadership role while struggling to hold onto a shred of her humanity.

X-MEN DISASSEMBLED

X-Men Disassembled Age of Apocalypse

After an extended absence, Nate Grey returned in Uncanny X-Men with a plan to dramatically reshape the Marvel Universe in his own image. When that put him at odds with the X-Men, Legion sent X-Man back to the Age of Apocalypse in Uncanny X-Men #6.

Unfortunately, several young X-Men got caught in the crossfire and were also sent to the Age of Apocalypse. Although Armor, Pixie, Rockslide and Glob Herman were all created years after the "Age of Apocalypse" crossover ended, these young mutants found themselves in the twisted bodies of their Age of Apocalypse counterparts.

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As tensions flared among the marooned mutants in Uncanny X-Men #7, these Young X-Men decided to kill Nate Grey, since he's considerably weaker in this world.

Since X-Man is set to be the centerpiece of the upcoming "Age of X-Man" crossover, it seems like that plan won't be too successful. However, it's not clear how the Age of Apocalypse could factor into that crossover. While it could be the basis for the mutant utopia that Nate seems set to establish, it could also just go on and continue to be the X-Men's worst, never-ending nightmare.