Spider-Man: The Animated Series did the Spider-Verse crossover first. In 2014, comic book writer Dan Slott pioneered an epic crossover event called "Spider-Verse." His goal was to write the ultimate interdimensional Spider-Man story, bringing together every alternate dimension version of the webhead he could imagine. He even managed to subtly write Tobey Maguire and Andrew Garfield's Spider-Men into canon.
The story proved tremendously influential,inspiring Sony's animated movie Spider-Man: Into the Spider-Verse. That story saw some more modern iterations of Spider-Man work together to save the Multiverse from destruction; it featured characters like Miles Morales, Spider-Gwen, Spider-Ham, and Spider-Man Noir. But, as enjoyable as these stories may have been, the idea of an interdimensional team-up of Spider-Men actually goes all the way back to Spider-Man: The Animated Series.
The fifth season of Spider-Man: The Animated Series climaxed in an interdimensional adventure in which Peter Parker was recruited to save the Multiverse. He was transported to another Earth, where he encountered a twisted version of himself who had been broken by a version of the Clone Saga. Broken by the realization he may really be a clone, this broken Spider-Man had fallen prey to the Carnage Symbiote. The combination of Spider-Man's scientific genius and Carnage's bloodlust had led him to create a device that would tear the entire Multiverse apart. The Spider-Man of the animated series was tasked to lead a group of alt-reality Spider-Men against him.
Spider-Man was somewhat shaken to find himself working as part of a team, and he found the five alternate Spider-Man more than a little disturbing. They included:
- A Spider-Man undergoing genetic mutation, partway through transforming into the Man-Spider.
- A Spider-Man who had become a billionaire industrialist, and who had developed advanced armor to allow him to serve as a superhero.
- Ben Reilly, the Scarlet Spider.
- A Spider-Man who had acquired Doctor Octopus' tentacles after defeating his arch-enemy.
- An actor who played a live-action Spider-Man in the real world.
Several of these Spider-Men appear to prefigure character arcs from the Slott run. Slott introduced the Superior Spider-Man, with Doctor Octopus' mind taking control of Peter Parker's body; later, he turned Peter Parker into a successful businessman for a time, placing him in charge of a multinational corporation called Parker Industries. He even brought back the Scarlet Spider as well. Frankly, it looks as though Slott quite liked this two-part "Spider-Wars" event.
This story ended with Madame Web giving Spider-Man a reward; a glimpse of a world where he was celebrated as a hero. He entered our reality, and got the chance to meet his creator, Stan Lee, who he thanked for turning him into a symbol of hope and justice. It was a strange note for a season to end on - made all the stranger because Spider-Man: The Animated Series was canceled after season 5, making that the end of the entire series.