Content Warning: This article contains discussions/references to death and violence.
controversial 1996 storyline that saw Marvel try to reboot the Avengers and the Fantastic Four. Though the MCU may have some interest in adapting the current story in the future, the original is best avoided. It's not the only comic crossover the MCU should steer clear of.
The best of the MCU so far has been based at least in part on some of Marvel Comics' biggest and best crossover events, like Civil War and The Infinity Gauntlet. But not all crossovers are created equal, however, critically or sales-wise. While the history of Marvel Comics is rich and deep, some of it is best left in the past.
Heroes Reborn
The original Heroes Reborn event from 1996 had the Avengers and Fantastic Four cast into a bubble universe, in which continuity had been completely reset. The origins and some details about the classic Marvel characters were updated for the modern era.
For instance, Ben Grimm was now a Gulf War vet and infamously, Rob Liefeld's rendition of Captain America - led to an end to the experiment in 1997.
Onslaught
The comic book crossover that instigated Heroes Reborn was the Onslaught saga. This story spun out of the X-Men books, where Onslaught, a terrifying fusion of the mental power of Professor X and Magneto, grew out of control. The story was an unsatisfying conclusion to a major mystery that had been brewing in the X-books for years at that point - who would betray the X-Men?
Bishop had come from the future with a warning about a potential traitor, leading to MCU-levels of speculation. In the end, the reveal was completely out of left field. The story also went on for a long time, encoming over fifty tie-in issues (a general problem with crossovers in the era).
Maximum Carnage
Carnage is set to make his live-action debut in Venom: Let There Be Carnage, and reactions so far seems mixed. It's likely to be better than the reception for Maximum Carnage, a major early 90s crossover featuring the villain.
Like Onslaught and other crossovers, the story sprawled into numerous Spider-Man titles of the period as Spider-Man and Venom teamed up to take down Carnage. Though the basic gist of the story could easily work in the context of the MCU, it would likely take some refining.
Secret Wars II
Secret Wars is the first major Marvel crossover involving all of its characters. The 1985 mini-series is often cited as a potential MCU storyline, but its sequel, Secret Wars II, is less well regarded. The original storyline has The Beyonder bring together all of Earth's heroes and villains. The sequel has him more or less walking around by himself.
The Beyonder explores his humanity in the sequel, which is an intriguing concept, but it manifests in unusual ways that didn't resonate with fans at the time. It also ends on a very tragic and sour note, with The Beyonder, now a human child, being killed.
Civil War II
Like with Secret Wars, the sequel to the very successful Civil War event didn't do as well as the original. Civil War II pitted Iron Man against Captain Marvel in a fight over the policing of potential crimes, which opens with the shocking murder of the Hulk.
While some aspects of less well-received by fans. One of the major issues was the portrayal of Carol Danvers, who comes off very militant in the story.
Secret Empire
Even more controversial was Secret Empire. This event revealed Steve Rogers as a secret HYDRA agent all along and conspiring with the group to take over America.
The idea of Captain America being a secret agent of the villains he had fought against for his entire life didn't really sit right with fans, even when the story seemed to leave open the door to other possibilities. Though Steve Rogers eventually returned and reclaimed the mantle from the 'evil' Captain America through some cosmic intervention, this one is best avoided in the MCU.
AXIS
The HYDRA Steve Rogers isn't the only evil version of Captain America from the comics. Another appeared in AXIS, a 2014 storyline. Onslaught makes an unexpected return here through the machinations of the Red Skull, who has acquired Professor X's brain.
He used his powers to invert heroes and villains, turning good guys bad and vice versa. The general problem was the simplicity of the storyline, stripping many characters like Namor or Doctor Doom of their shades of gray and making everyone black and white.
The Crossing
Heroes Reborn wasn't the only controversial 90s Marvel storyline. The Crossing preceded it, and like Secret Empire, shocked fans by revealing a major hero was a villain all along. Tony Stark is revealed to be a secret agent of Kang The Conqueror, and he then goes on a murderous rampage to cover his tracks.
Iron Man is eventually killed in the ensuing struggle and he's replaced by a teenage version of himself from an alternate timeline. Marvel eventually swept the story under the rug through the Heroes Reborn reboot, when an adult Tony returned from the bubble universe and fused with the teenage version.
Ultimatum
Ultimate Comics started in the early 2000s in the alternate world of Earth-1610. This sub-line gave classic Marvel characters like Spider-Man a fresh modern start without the weight of previous continuity.
The promise of the fresh start eventually was lost in Ultimatum, a crossover that featured over-the-top violence and some of the most disturbing scenes in Marvel Comics history. Fans reacted negatively to the murder of The Wasp by The Blob and Magneto's destruction of Wolverine.
The Clone Saga
Crossovers and twists were common in the '90s, an era marked by excess in the comics industry. The Clone Saga might be the epitome of it. This sprawling storyline encomed the better part of two years and numerous books to tell the story of Ben Reilly, the clone of Peter Parker.
The original story was meant to be much shorter, but a modern version of The Clone Saga is coming in the comics this year.