For a long time, comics have dealt with the notion of alternate universes and the opportunities that arrise from severely changing the status quo of any hero or villain. Dan Slott and Oliver Coipel build on this concept by uniting Spider-Man with countless versions of himself in a desperate battle for survival. The Spider-Verse allowed fans to see Peter Parker interact with his fellow arachnids from across the Marvel Multiverse.
Although Spider-Verse is arguably the most popular of these events, spawning its own film adaptation and franchise, plenty of other Avengers have had similar encounters with alternate versions of themselves.
Venom
In the pages of Venomverse, Eddie Brock, shortly after resuming the role of Venom, learned the symbiotes of the multiverse and their respective hosts had become the targets of an alien species known as the Poisons, or Hive. Recruited by a venomized Doctor Strange, Eddie found himself as a member of the Resistance. The ranks of the symbiote warriors included X-23, Black Panther, Rocket Raccoon and even Spinneret (the Mary Jane of the Renew Your Vows universe).
Like the Inheritors of Spider-Verse, the Poisons wanted to consume symbiotes and their hosts, in order to create poisoned versions to add to their ranks. As this confrontation came to an end, the Resistance also recruited Carnage, as well as a Poison Deadpool, who had broken free of the Hive's control. Although this group of Venoms defeated the Hive, the Poisons would later return to the main Marvel Universe, forcing Venom to work with the All-New X-Men and the other Marvel heroes.
Deadpool
Recruited by the Contemplator, an elder of the universe, Wade Wilson was tasked with recruiting other versions of himself in a battle against the Awareness, a cosmic force bent on consuming the consciousness of the multiverse. Given his "unique" perspective and ability to break the fourth wall, only Deadpool could stop this force, which required him to recruit backup of a similar mindframe. The Deadpool Corps' original members included Lady Deadpool, Headpool (hailing from the Marvel Zombies timeline), Kidpool and Dogpool.
Given Deadpool's usual inability to be a cohesive team member, a whole team of Wades (and Wanda) quickly fell apart after defeating their intial target. However, the team returned during the events of Deadpool Kills Deadpool, written by Cullen Bunn and Salva Espin. Just as in Spider-Verse, this series showed the many Deadpools of the universe targeted for extermination by one version of the Merc with a Mouth that had decided to put an end to the constant cycle of their comic book realm.
Wolverine
During the Exiles series from Tony Bedard and Paul Pelletier, the Timebroker reached into the multiverse to recruit multiple versions of everyone's favorite mutant. Unlike the other cases, this team did not feature the classic Wolverine from the main Marvel Universe. Instead, the Timebroker took Wolverines from parallel timelines, like a zombie Wolverine and Major Logan from the Days of Future Past future, as well Wolverine from different points in his life, such as a young James Howlett and a still-controlled Weapon X.
The Timebroker recruited the Wolverine Squad to face an enemy known as the Brother Mutant, which was an amalgamation of Wolverine, Scarlet Warlock (a male version of Scarlet Witch), Magneto, Quicksilver and Mesmero. During this battle, the team also relied on other versions of Wolverine in their attempt to free this reality from the monster. Unfortunately, they did not survive their first battle, as the Exiles were forced to pick up the pieces.
Mister Fantastic
Created out of the infinite set of Nathaniel Richards that were pulled from each of their universes, the Interdimensional Council of Reeds consisted of Reed Richards from alternate universes who had come to prioritize the accumulated needs of the multiverse over their own homes. This group used their intellect to solve humanitarian problems in certain universes and to remove threats like Galactus and Doctor Doom. Unlike his counterparts, the Reed Richards of the main Marvel Universe could not leave his family for this new mission.
This group was nearly destroyed in their battle with a set of mad Celestials who sought their technology. In recent years, the group has become less restricted in their approach, allowing their members to remain within their own families. Their most recent endeavor has been led by the Maker, the Ultimate Reed Richards, who has been concerned with Venom and Knull.
Thor
At the beginning of his run on Thor, Jason Aaron brought Thor to face both his younger self -- a Thor that was not yet worthy -- and his future version -- known as King Thor -- in his battle against Gorr, the God Butcher. Following this encounter, Aaron also featured multiple versions of Thor as a police force for Emperor Doom in the pages of Secret Wars. Although this group had plenty of hammers, the most epic team-up between Thors was shown in his final battle against Malekith.
As the War of the Realms came to a close, Thor's parents, Odin and Freya, were captured and surrounded by a force field that only Thor could enter. Besides his past and future selves, Thor was also joined by Jane Foster, who used the Mjolnir from the Ultimate universe. Together, these versions of Thor defeated Malekith and brought Thor's hammer back into the fold.