With the release of Secret Wars In 1984, Marvel Comics introduced its very first comic book crossover event. The origin of the crossover was simple enough. Mattel, a toy manufacturing company, was in a partnership with Marvel and wanted to produce a set of themed action figures. After providing the comic book company with directives about what it was looking for, the resulting event was a game-changer for the entire comic book industry.

Jim Shooter, Michael Zeck, John Beatty, Christie Scheele, and Joe Rosen created a 12-issue series that brought most of Marvel's main heroes together for the first company-wide crossover in history. Secret Wars was a massive success, and here is a look at what led to it, what happened in the story, and the impact the event had on Marvel Universe.

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THE LEAD-UP TO SECRET WARS

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The original Secret Wars was unique in that it had no "tie-in" issues that needed to be purchased in order to fully experience the story. This series was a one-of-a-kind self-contained event that started and ended within the 12 monthly issues.

The only lead-up to Secret Wars arrived at the end of several Marvel Comics just prior to the release of the first issue, wherein the heroes involved in the event disappeared with no explanation. The next month they returned with very little explanation, in some cases with major changes that occurred as a result of the event. Secret Wars tells the story of what happened in between the issues.

WHAT HAPPENED IN SECRET WARS?

Secret Wars Cropped

A mysterious and omnipotent being known only as The Beyonder kidnapped most of Earth's greatest heroes and villains and transported them to an alien planet known as Battleworld. Everyone involved watched The Beyonder destroy an entire galaxy to create this planet, and heroes and villains alike realize he is more powerful than almost anyone they ever faced. All the heroes appear in one construct, along with Magneto, while all the villains appear in a different one. As the name of the world implies, this was a battle between heroes and villains — all for Beyonder's entertainment.

The gathered villains begin to fight one another almost immediately. Ultron tries to destroy them all, but Galactus drains all the energy from the robot before he ignores everyone and stares off into the stars. When The Beyonder explains what he expects everyone to do and promises the winner will get anything their heart desires, Galactus tries to face him head-on to no avail. Meanwhile, the heroes suffer a split-up as well with the majority of them distrusting Magneto and the X-Men.

As the battle between the heroes and villains begins, Doctor Doom diverts his attention into a quest for more power. He finds a way to steal The Beyonder's power, and declares himself the lord of Battleworld, with heroes and villains alike at his mercy. The conclusion of the series revolves around the assorted heroes and villains working together in a concerted effort to defeat a massively overpowered Doom while attempting to find a way back to Earth.

RELATED: How Did Cyclops Get To Battleworld In Secret Wars?

HOW SECRET WARS CHANGED THE MARVEL UNIVERSE

Debut of the alien symbiote costume worn by Spider-Man during Secret Wars

While Secret Wars tells the story of the battle between heroes and villains, the treachery of Doctor Doom, and the journey back home, the real impact of this series is what happened once it ended.

The most significant change was when Spider-Man returned to Earth with a new black costume. This costume seemed to react to Peter Parker's thoughts and gave him a power boost. The outfit turned out to be the alien symbiote that would become Venom, and it was Secret Wars that saw the symbiote come to Earth for the first time.

Another significant change happened in the pages of The Fantastic Four. The team experienced a major roster change upon returning to Earth as The Thing was now gone and replaced by She-Hulk. It was later explained that while on Battleworld, The Thing was able to transform back to his human form at will, so he chose to remain behind and explore the planet while She-Hulk took his place on the team. Secret Wars also introduced Julia Carpenter, the second Spider-Woman who evolved into Madame Web, and the villains Titania and Volcana.

Another Secret Wars series ripped through the Marvel Universe three decades later, ending with the destruction of the Multiverse. However, as much as the new series shook up the Marvel Universe, the original was still the first of its kind.

KEEP READING: Marvel's Secret Wars II Was Ahead Of Its Time