There have been many dark potential timelines for the Marvel Universe, where the defenders of the Earth fail in their mission to save the world. In two of Marvel's most famous dystopian timelines, major villains were able to take control of the world and wipe out almost all of their potential enemies. In the '90s and '10s, the Age of Apocalypse and Age of Ultron both took over a decent chunk of the Marvel Universe for several months.
Now, we're taking a closer look at both of these post-apocalyptic superhero landscapes to see which one was really worse and more horrifying to live through for the surviving X-Men and Avengers.
HOW BAD WAS THE WORLD OF AGE OF APOCALYPSE?
The world of Age of Apocalypse was caused by Legion, the son of Charles Xavier, after he traveled to the past to try and change the future. His attempts to give his father an advantage in bringing mutant/human peace by killing Magneto backfires though when Xavier sacrifices himself to save his friend. This erases Legion and the assembled time-traveling X-Men from existence, except for Bishop, who'd absorbed enough of Legion's reality-warping powers to survive. Meanwhile, the battle with Legion was so destructive that it awoke the mutant-despot Apocalypse decades early, meaning there were no trained heroes around to protect the world from him and his influence. This led to a dark future where many heroic characters were corrupted and Apocalypse could rule the world with his iron fist.
Within 20 years, the world had been reduced to a dystopic, largely nuclear ruin. Apocalypse rules over a despotic and brutal mutant totalitarian government from his seat of power in what used to be New York City, with his edicts carried out by his Prelates. Most of humanity has been wiped out and converted into fuel for the armies of Apocalypse, although there are some pockets of life in isolated locations such as in Europe and the Savage Land. Only the X-Men remain to fight his soldiers, led by Magneto. But dwindling numbers, impossible odds, and a looming nuclear war make the world seem hopeless until Bishop finds the X-Men and reveals the truth about the original reality to Magneto, which sets up the team to help restore the original timeline.
HOW BAD WAS THE WORLD OF AGE OF ULTRON?
After returning to the Earth, the robotic villain Ultron turned his attention on finally wiping out humanity once and for all in Age of Ultron. A massive army of Ultron drones are assembled and unleashed, leading directly to the demise of most of the heroes who tried to fight back against his forces. Only a handful survived, left with barely any supplies in an increasingly hostile environment. Some heroes like Black Widow were able to procure Nick Fury's old plans to contend with Ultron and rejoined with the others to convince them to take that route. The last of the heroes come up with a desperate plan to stop Ultron head-on, using Doctor Doom's Time Platform to attack Ultron directly in the future.
However, Wolverine comes up with a different scheme - using the Time Platform to instead assassinate Hank Pym before he ever constructed Ultron in the first place. While the initial team was quickly killed by Ultron during the attack and he was able to fully assert his control over the world, Wolverine and Invisible Woman successfully changed the future by killing Pym. But this merely caused an even darker reality where Morgan Le Fay had been able to take over half the world after magic "broke" technology, which forced Wolverine to head back and change the timeline again by instead revealing to Pym that he'll need to install -- and then forget until the right moment -- a secret aspect of Ultron's programming that could shut him off remotely, thus saving the timeline.
WHICH DARK FUTURE WAS THE MOST TERRIFYING?
Neither the Age of Apocalypse nor the Age of Ultron is exactly pleasant. Both dark futures of the Marvel Universe are places where a majority of the civilian population has been wiped out. Still, the Age of Apocalypse remained a world with some hope in it. The X-Men served as heroes to both humans and mutants, helping save lives and bring down villains. Members of Apocalypse's own government, notably Sinister's lieutenant Cyclops, turned against him and worked to save human lives. Even the apparent destruction of everything at the climax of the story while the M'Kraan Crystal restored the original timeline was later revealed to not be the case, with the Age of Apocalypse world surviving for a time. Although it would eventually be destroyed fully, some survivors escaped by finding homes on new realities.
Contrastly, Age of Ultron is a very bleak look at a potential future for the core Marvel Universe. Seeing Ultron fully unleashed led to the death and destruction of almost everything on the Earth, with even fewer heroes existing than in the Age of Apocalypse. The few that remain even ultimately die in their attempt to save the world, proving their efforts to fight Ultron were all for nothing. And while Bishop was able to fix the original Marvel timeline by saving Magneto's life, Wolverine was forced to kill to try and do the same. That inherent difference in what it takes to save these worlds can indicate just different they are. For all its faults, at least the heroes could still be heroes in the Age of Apocalypse. In the Age of Ultron, they just ended up dead, which is far more sad and hopeless.