Before Spider-Man: Into the Spider-Verse -- even before Dan Slott's Spider-Verse stories in the comics and video games that inspired that film -- the '90s Spider-Man animated series told a reality-bending story that teamed Peter Parker up with his doppelgangers from various different timelines.
You can see a video examining the episodes, and comparing it to what came later, above.
It is, perhaps, not entirely surprising that this is a thing that happened. Between Spider-Man and X-Men, the Marvel cartoons of the '90s often embraced the complexities and subtle madnesses of long-form superhero storytelling more openly than any previous adaptation had done until The CW came along and started to make things like the multiverse a live-action reality years later.
The story was "Spider-Wars," and it was building to a massive finale to the animated series. Following an adaptation of "Secret Wars," the producers wanted Spider-Man to save all of reality, and in order to do so, he basically had to lead a team of alternate-reality Spider-Men to defeat his ultimate foe -- a version of Peter Parker who was bonded with the Carnage symbiote.
...And, yes: before Slott did it in the comics, the Japanese Spider-Man gets a nod here, too. And maybe the greatest Stan Lee cameo of all time.
Please note that "before Slott" has come into this a few times, and that is not meant -- either by us, or by the folks at Panels to Pixels, who made this video -- to imply anything bad. First of all, Slott's story takes inspiration from the "Spider-Wars" story pretty openly, so it is not as though he was "copying" anything. And both his Shattered Dimensions video game and the Spider-Verse storyline took the concept and ran with it, utilizing the comics' history and incorporating characters and concepts that made it bigger and grander than anything the animated series had bandwidth for, and laying the foundation for what would become the Into the Spider-Verse feature film.
But it is nevertheless fun to look back on the time that somebody actually animated an army of variant Spider-Men together, battling a mastermind bent on breaking reality with Peter at the center of it all.
Spider-Man: Into the Spider-Verse is in theaters now.