If a setting has Alternate Universes, then there is probably more than one version of the main character. If there are an infinite number of universes (or even just 52) then there will be lots of versions of the main character. So what's better than meeting one of them?
Meeting all of them at once! This gives lots of opportunities for Other Me Annoys Me bickering, while at the same time most versions of the character can find some version they can get along with. If Evil Me Scares Me, they could be there too, but at least they'll probably be outnumbered. The most important thing, though, is that they'll all be able to fight a common foe that previously overpowered them, or accomplish a significant goal.
Time-travel examples, such as a character meeting his past or future self/selves, don't count unless the mechanics of the work mean time-traveling creates a different universe. For a meeting of selves from the same universe, see Me's a Crowd. When other selves simply meet or exist without necessarily teaming up against someone or something, see Alternate Self.
- In the last episode of Digimon Adventure 02 the characters get blasted into another dimension that makes wishes into reality. When they ask for more power they split off into all of their alternate forms. For example Davis is able to summon Veemon, Flamedramon, Raidramon, Exveemon, Paildramon, and Imperialdramon in both dragon and fighter modes all at once where in a regular battle Veemon would only be able to transform into one of the above. Multiply this by the 6 main characters and they form a small army.
- In Dragon Ball Super, Goku Black and Future Zamasu whom the former is actually present Zamasu who stole Goku's body both team up together to accomplish their plan for mortal extermination.
- In the Marvel Universe:
- Kang the Conqueror has the Council of Cross-Time Kangs, formed to rule multiple realities. They clashed several times with the Avengers during their plans.
- Fantastic Four homaged the Council of Kangs with the Interdimensional Council of Reeds, led by three versions of Reed Richards with Infinity Gauntlets. Earth-616's Reed quickly discovers that their For Science! attitude clashes with his own morality and sense of family.
- Also the Captain Britain Corps, although not all of them are alternates of Brian Braddock (but many of them are). They're basically mystically powered protectors of the multiverse under the direction of Roma and Opal Luna Saturnyne.
- The plot of Spider-Verse is all the Spider-Men of different realities teaming up to stop Morlun and his family from killing all the Spider-Totems. The short-lived Web Warriors continued this, with a team of Spiders protecting the multiverse.
- In one arc of Exiles an Exiles team of Wolverines from assorted realities band together to stop an evil Wolverine from yet another reality.
- Deadpool has teamed up with several alternate universe versions of himself to form the Deadpool Corps. which include: Lady Deadpool, Kidpool, Dogpool, and Headpool. They join forces to stop the villainous Dreadpool.
- Played for Laughs in Deadpool: Too Soon where multiple Wolverines are having a baseball match against multiple Spider-Men (yes, the ones from the Spider-Verse example above) and Deadpool shows up as a supporter of both teams.
- Venomverse is a darker parallel to Spider-Verse where Venom must team up with alternate incarnations of the symbiote to fight a threat called the Poisons.
- In The DCU:
- In The Multiversity: Thunderworld, Dr Sivana contacts other universes to form a League of Sivanas. Notable members include a cartoon snake (presumably the enemy of Earth-26's Hoppy the Marvel Bunny), a Torture Porn-themed depraved serial murderer Sivana in a bite-mask who even gives Thunderworld!Sivana the creeps, and a respectable scientist who's horrified to realise the others are all criminals.
- During Final Crisis, Superman and The Question recruit the Supermen of the Multiverse, who face down Ultraman and eventually Darkseid.
- The various incarnations of the Legion of Super-Heroes teamed up in Final Crisis: Legion of 3 Worlds against Superboy-Prime, starting with Reboot, Retroboot and Threeboot, but later including the 5 Years Later Legion, the SW6 Legion, the Silver Age Adult Legion and so on.
- An arc of the 90's Superboy series ("Hyper-Tension!") had various versions of Kon-El (and a couple of Clark Kent) allying themselves to fight a version of Kon that was grown up, more powerful because of his age, and so Drunk on the Dark Side that he became a Multiversal Conqueror.
- During Dark Nights: Metal, the Dark Knights of Barbatos are this, consisting of 7 Batmen from the Dark Multiverse, each twisted by a fear, regret, and tragedy that the Prime Bruce Wayne has... all empowered further to make them counterparts to the Justice League.
- At one point, villain Angstrom Levy in Invincible gathers Evil Twin type alternates of the hero Invincible from Mirror Universes to kill him and take over the world.
- One issue of Simpsons Super Spectacular had three versions of Bart who are superheroes (Bartman from "Three Men and a Comic Book", Stretch Dude from "Treehouse of Horror X" and Cupcake Kid from "Simple Simpson") sent to a Mirror Universe to overthrow King Bart, it was titled "League of Extraordinary Barts".
- Captain Valor attempts this at the start of Hero Squared. Sadly, the alternate version he goes to for help never got superpowers in this universe and is just an immature slacker.
- The final battle of Tokumei Sentai Gobusters Returns Vs Dobutsu Sentai Gobusters involves the alternate Go-Busters teaming up with the regular ones.
- Stargate SG-1: In "Ripple Effect", a whole bunch of alternate SG-1s arrive in the SGC because of black hole-related technobabble, and the various Carters all have to work together to fix the problem.
- The Flash (2014): In "When Harry Met Harry", Harrison "Harry" Wells of Earth-2 calls upon three of his doppelgangers from other Earths into the so-called "Council of Wells". One is a stuck-up German physicist named Harrison Wolfgang Wells (Earth-12). The second is a "genius, billionaire, playboy philanthropist" from Texas named H. Lothario Wells (Earth-47). The third is an Australian cyborg from the post-apocalyptic Earth-22 named Wells 2.0. Yet another Wells attempts to join the Council, only to be rebuffed. He calls himself Wells the Gray and is dressed as Gandalf.
- The Council of Wells was revisited in "Harry and the Harrisons", where Harry goes to the Council for help because one of his inventions had given him brain damage — and Herr Wells kicks him out for failing intelligence requirements. He forms a new "Council of Harrys" out of other alternates: the French Harrison H.P. Wells, Totally Radical New Yorker Sonny Wells, and Lothario Wells again (who Herr Wells also kicked out of the original Council).
- Brainiac's plan in Scribblenauts Unmasked is to steal Lily's teleporting globe and use it to summon alternate universe versions of himself to defeat the Justice League. The key to defeating him potentially uses the same trope- You have to summon alternate versions of superheroes, so you can, if you wish, have a dozen different Supermen fighting the Brainiacs.
- The new, "true" Organization XIII in Kingdom Hearts 3D: Dream Drop Distance has a membership consisting of various versions of Master Xenahort.
- Spider-Man: Shattered Dimensions had four different Spider-Men — Amazing, 2099, Noir, and Ultimate — all working together.
- Spider-Man Unlimited has the player collect different multiversal Spider-Men and pits them against an opposing alliance of alternate Sinister Sixes.
- Homestar Runner: In Strong Bad Email #150, "alternate universe", Strong Bad and some of his alternate selves end up in his home dimension, and he convinces his dimensional doppelgangers to form a supergroup and record a number one jam.
- The Floating Hands parody animation "Fantastic Four: Doomsday" features Doctor Doom teaming up with versions of himself from alternate continuities.
Doom: If you want something done right, you do it yourself. With yourself.
- Homestuck is full of these. The time-travel mechanics of a Sburb session almost always end up creating offshoot timelines overlapping with the main one. Scratching a session creates a new universe where the players and guardian roles are swapped. It is thus easy to meet and work with counterparts.
- Aradia gathered thousands of alternate selves to help fight the Black King in the troll session.
- Jane finally meets her pre-Scratch counterpart Nannasprite before the final battle. And there's a second Nannasprite due to the retcon. They end up fighting together.
- Thousands of ghost versions of the troll players from doomed timelines are brought together to fight Lord English near the end of the comic.
- In Spinnerette, Spinny teams up with Silver Age and '90s Anti-Hero versions of herself, which arrived through spacetime rifts, in order to stop an immensely powerful supervillain called the Editor from "rebooting" the world. Then they also met the retired Golden Age version... who revealed that the Editor's "reboot" was not The End of the World as We Know It, but rather the creation of yet another Alternate Universe, this one IN SPACE!.
- Goblins has the Maze of Many arc, in which Minmax and his allies travel to a Pocket Dimension where multiple realities overlap and multiple instances of the same person can exist at once. Kin is invited to join a Kins-only team consisting of Kins from other realities, and several different Minmaxes team up against another Minmax when they realise he's trying to erase the Maze, and everyone inside it, from existence.
- Batman: The Brave and the Bold: In "Game Over for Owlman!", where Batman has to fight an evil alternate universe version of himself (Owlman) who is the leader of an evil alternate universe version of the Justice League, he manages to gather a team of heroic Batman alternates to fight the villains.
- Ben 10: Omniverse had a two parter which involves Ben and his AU counterparts (as well as an AU Gwen, who had that universe's Omnitrix) teaming up to Stop Eon and Vilgax form enacting an Evil Plan. There are 2 twists involved: Vilgax and Eon also have their own army of AU!Bens (and Albedo), and that part ends with Vilgax pulling a multiverse-scale Cosmic Retcon that erases everyone with the Omnitrix, leaving only one Ben behind, becuase he didn't get his verse's Omnitrix. The next episode focus on reversing this.
- The Fairly Oddparents: In "The Crimson Chin Meets Mighty Mom and Dyno Dad", Timmy called forth the many version of the Crimson Chin from the 30s pulp version to the 80s Edgy version to defeat the Nega-Chin.
- Turtles Forever centers around the team up of the 2003 version of the TMNT and the 1987 version. In the finale the turtles from issue 1 of the original comic book series in 1984 also join. In the end you have 12 turtles, 3 versions of each of the four brothers.
- Ultimate Spider-Man had its own version of Spider-Verse; a multipart story where Peter teamed up with Spider-Man 2099, Spider-Woman/Petra Parker, Spider-Man: Noir, the Spectacular Spider-Ham, Medieval Spider-Man, and Miles Morales to stop the Green Goblin from stealing their DNA. Interestingly, he didn't meet them all at once, but instead travelled from a dimension to another, until the end where they all come back together.
- The finale of Spider-Man: The Animated Series had Spidey teaming up with multiple alternate dimension versions of himself to save the universe with the help of Madame Web and The Beyonder. They include a Tony Stark style inventor engaged to Gwen Stacy (who "our" Spidey had never even met), a version of Ben Reily, a Spidey still having multiple arms due to a mutation problem, a Spidey with Doc Ock arms, and an actor with no powers who plays Spidey in movies, hailing from a universe where Spider-Man is just a famous comic character created by Stan Lee.
- A parody of the Council of Reeds from Marvel Comics, the Council of Ricks in Rick and Morty are hundreds of Rick Sanchezes from across the multiverse who founded the alliance in order to escape the authorities that hunt them down in their own respective universes. Rick C-137 is one of the few Ricks who looks to the council with contempt, seeing the council as an abandonment of the "lone wolf/every-Rick-for-himself rebel" mindset that Ricks were originally defined by and becoming the very thing they hate. The Council in-turn see Rick C-137 as a loose-cannon with an unhealthy, passionate attachment to his Morty (which the Council see as nothing but accessories that could be switched out and replaced) that could potentially undermine their entire organization.