- The Fantastic Four
- Confirmed as part of the expansion pass.
- Hawkeye
- Confirmed.
- Doctor Strange
- Confirmed.
- Black Panther
- Confirmed.
- Ant-Man
- Appears as an NPC helping in the Ultimo boss fight.
- The Wasp
- Confirmed.
- Cyclops
- Confirmed as free DLC.
- Jean Grey / Dark Phoenix
- Phoenix is confirmed to be part of the X-Men DLC pack. Dark Phoenix can be fought in the Danger Room and Gauntlet modes.
- Iceman
- Confirmed as part of the X-Men DLC pack.
- Beast
- Appears as an NPC.
- Angel
- Colossus
- Confirmed as free DLC.
- Nightcrawler
- Confirmed.
- Storm
- Confirmed.
- Psylocke
- Confirmed.
- Shadowcat (with Lockheed)
- Rogue
- Jubilee
- Cannonball
- Magik
- Wonder Man
- Blade
- Confirmed as a playable DLC part of the Marvel Knights expansion pass.
- Ghost Rider
- Confirmed
- She-Hulk
- A-Bomb (Rick Jones)
- Captain Marvel
- Confirmed.
- Magma
- Ms. Marvel
- Confirmed.
- Black Bolt
- Appears as an NPC.
- Medusa
- Appears as an NPC.
- Karnak
- Gorgon
- Appears as an NPC.
- Triton
- Captain Britain
- Black Knight
- Miles Morales
- Confirmed.
- Spider-Gwen
- Confirmed.
- Bombshell
- Namor
- White Fox
- Gambit
- Confirmed as part of the X-Men DLC.
- Doctor Doom
- Confirmed as part of the Fantastic Four DLC.
- Magneto
- Confirmed.
- Songbird
- Taskmaster
- Deadpool
- Confirmed.
- Venom
- Confirmed.
- Green Goblin
- Appears as a boss.
- Carnage
- Doctor Octopus
- Appears as a boss.
- Nova
- Richard Rider and some unnamed members of the Nova Corps appear as NPCs.
- X-23
- Darkhawk
- Moon Knight
- Confirmed as a playable DLC part of the Marvel Knights expansion pass.
- Emma Frost
- Daredevil
- Confirmed.
- Kate Bishop
- Gwenpool
- Luke Cage
- Confirmed.
- Iron Fist
- Confirmed.
- White Tiger
- Cloak and Dagger
- Juggernaut
- Appears as a boss.
- The Punisher
- Confirmed as a playable DLC part of the Marvel Knights expansion pass.
- Moon Girl and Devil Dinosaur
- Squirrel Girl
- Quicksilver
- Spider-Woman
- Winter Soldier
- Appears as an NPC.
- Black Cat
- Sabretooth
- Cable
- Confirmed as part of the X-Men DLC pack.
- Man-Thing
- Boom Boom
- Monica Rambeau (as either Photon or Spectrum)
- Machine Man
- The Sentry
- Shang-Chi
- Gargoyle
- Interloper
- Red Guardian
- Jocasta
- Protector
- Silver Surfer
- H.E.R.B.I.E.
- Howard the Duck
- The Amazing Slapstick
- Silver Sable
- Peggy Carter
- Tigra
- Ikaris
- Sersi
- Makkari
- Kingo Sunen
- Sprite
- Thena
- Gilgamesh a.k.a. the Forgotten One
- Phastos
- Zuras
- Cybele
- Aginar
- Ransak the Reject
- Karkas
- Ajak
- Slipstream the Eagle
- Lionheart the Lion
- Wreckless the Grizzly Bear
- Surfstreak the Dolphin
- Hip-Hop the Kangaroo
- Comet Man
- The Human Fly
- American Eagle
- Shamrock
- Arabian Knight
- Blitzkrieger
- Ka-Zar and Zabu
- Alex Power
- Julie Power
- Katie Power
- Jack Power
- Hyperion
- Power Princess
- Nighthawk
- Doctor Spectrum
- Union Jack
- The Choir
- Snakes
- Kelpie
- Britannia
- Jack of Hearts
- Dominic Fortune
- The Masked Raider
- The Rawhide Kid
- Omega the Unknown
- Justice
- Firestar
- Night Thrasher
- Speedball
- Rage
- Namorita
- Scarlet Spider
- Hellcat
- Silk
- Spider-Ham
- Spider-Man 2099
- Spider-Man Noir
- Peni Parker & SP//Dr
- Phil Coulson
- Quake
- Red Sonja
- Conan the Barbarian
- ROM Spaceknight
Nintendo guest characters
- Link
- Zelda
- Ganondorf
- Samus
- Donkey Kong
- Mario
- Luigi
- Bowser
- Pit
- Captain Falcon
- Little Mac
- Fox McCloud
- Falco Lombardi
- Marth
- Ike
- Shulk
- Rex (with Pyra / Mythra)
- Kirby
- If possible, perhaps even the Mario Bros. or Bowser may end up as playable. After all, Mario has made crossovers with SSX of all things.
- Alternatively, maybe with Wonder-Red, Captain Falcon, Spring Man and Captain Rainbow.
- If possible, perhaps even the Mario Bros. or Bowser may end up as playable. After all, Mario has made crossovers with SSX of all things.
- Bayonetta is highly unlikely, since those games are owned by SEGA, Nintendo has only helped publish them.
- Confirmed... somewhat. It's a distillation of the entire Marvel Universe (mainly stories from the '90s onward), but those are the main inspirations.
- Confirmed by Game Informer, though most of the costumes are only Palette Swaps. Proper alternate costumes are added through free updates.
- OG Venom is confirmed, nothing for Anti-Venom so far.
- Anti-Venom was added post-launch as an alternate costume for Venom.
- Confirmed. While Thanos is still fought at the end, he does get his Big Bad role taken by his son, Thane; who not only becomes the True Final Boss and seizes the Infinity Gauntlet, but uses it to obtain an entire armor made out of the same material named the Infinity Armor; which Thanos refused to use beyond the Gauntlet due to it bearing uncontrollable amounts of power. As a result of Pragmatic Villainy, Thanos teams up temporarily with the heroes to defeat his son.
- The Eternals — This one's kind of a given if they do DLC, since it would be a perfect way to tie in with their MCU movie. They could give us a team consisting of Ikaris, Sersi, Thena, and Gilgamesh/The Forgotten One.
- Squadron Supreme — Needs More Love, plus it would technically be the closest thing we could get to the Justice League in an Ultimate Alliance game. Team could consist of Nighthawk, Hyperion, Power Princess, and Doctor Spectrum.
- Young Avengers — Same reason as The Eternals (if they get a movie). They could provide a team consisting of Wiccan, Hulkling, Hawkeye/Kate Bishop and Stature.
- NextWave — Curveball suggestion, for Rule of Funny.
- Elsa made it into the base roster, at least.
- Multiversal counterparts — Interesting characters from the wider Marvel Multiverse, such as Old Man Logan, Spider-Ham, and Cosmic Ghost Rider.
- Runaways — A solid suggestion as they're well-regarded but often kept out of crossovers. Could include Nico Minoru, Chase Stein (w/ Old Lace), Karolina Dean, Molly Hayes and Victor Mancha.
- Power Pack — Cult Classic kid-team and it's rumored they'll be getting a Disney+ series, making it a solid idea. The team is obvious: Alex, Julie, Jack and Katie Power.
- The Fantastic Four — As of this edit, we haven't seen any sign of Marvel's first family, despite them being in the same situation as the X-Men and treated very similarly (barred from adaptations due to issues with movie rights). Whether they're completely absent from the base game or they simply show up as NPCs, it's possible they're being saved for future DLC. Besides the Four themselves, the team could include their nemesis Doctor Doom, as well as related characters like Namor, Silver Surfer, She-Hulk, Namorita, and possibly one of the Inhumans.
- Content for the Fantastic Four is confirmed for DLC. It includes the Four themselves as well as Doom as playable characters, along with a story epilogue dedicated to them.
- Future Avengers — Doubles as cross-promotion for the anime, which is all but confirmed to get an English dub soon. The team consists of Makoto, Adi, and Chloe.
- The New Warriors
- War of the Realms — Valkyrie and Hela could be added as characters; and Malekith, Kurse, Jack O'Lantern, and Jane Foster Thor/Valkyrie could be added as new characters
- Carnage — Given that he was a popular DLC character from the previous game, Carnage returning as a DLC character in Ultimate Alliance 3 — with a "story mode" gauntlet referencing Maximum Carnage and/or Absolute Carnage — makes sense. Shriek, Demogoblin, and Doppelganger could be made additional playable characters as well.
- NPCs and Bosses — The DLC for previous games included characters who were already in the game in some form (Doctor Doom and Nightcrawler in the first, Black Panther and Cable in the second) but weren't actually playable, so this game might follow suit with characters like Thanos and Nebula. It helps that some of the (currently known) NPCs in this game (Cyclops, Colossus, Beast, Juggernaut, Nick Fury, and Green Goblin) were playable in previous games, and some were originally going to be playable before being Dummied Out, so DLC could be a good way to bring them back
- Cyclops and Colossus will become free DLC characters, so partially confirmed. Also, Thanos is not DLC, but unlockable by finishing the main campaign.
- Captain America
- The Captain
- U.S.Agent
- Nomad
- Bucky Barnes's Captain America costume
- Punisher's Captain America costume
- Soldier Supreme.
- Super Soldier
- Confirmed as DLC (it's the maskless costume from The Heroic Age).
- Poison Captain America
- World War II
- Iron Man
- Endo-Sym
- Extremis
- Confirmed as DLC
- Hickman's Avengers
- Prototype (original, beta armor)
- Ultimate
- All-New, All-Different Marvel
- War Machine
- Iron Patriot
- Hulk
- Gray (his original look)
- Confirmed as alternate palette
- Joe Fixit
- Immortal
- Professor Hulk
- Planet Hulk
- Confirmed as DLC
- Green Scar
- Red Hulk
- Doc Greene
- Poison Hulk
- Gray (his original look)
- Thor
- '90s
- Ultimate
- Confirmed as DLC
- Odinson (Unworthy Thor)
- All-Father Thor
- Black Widow
- Gray ('80s costume)
- Yelena Belova
- Confirmed as DLC
- Red Widow (Ava Orlova)
- All-New, All-Different Marvel
- Hawkeye
- Classic (pointy mask)
- Ultimate
- Ronin
- Confirmed as DLC
- Falcon
- Classic (red and white)
- There is an alternative palette based on it.
- Sam's Captain America suit
- Thor Falcon
- He got his Ultimate costume instead.
- Classic (red and white)
- Scarlet Witch
- Classic
- Confirmed as DLC
- Ultimate Marvel
- Marvel Now!
- MCU
- Transia (her Romani inspired outfit)
- Classic
- Vision
- Classic
- He is an NPC, so no costume change
- Classic
- Captain Marvel
- Classic Ms. Marvel<!—this is the one inspired on the original Captain Marvel, with the scarf—>
- Warbird (yes, the infamous leotard)
- Confirmed as DLC
- Sharon Ventura/She-Thing.
- Binary
- Warzone Carol.
- Sentress.
- Black Panther
- Classic
- Golden Suit
- Civil War
- Thrice-Blessed Armor
- Confirmed as DLC
- Ant-Man
- Classic (comic design with the open mouth)
- Eric O'Grady
- Future Foundation.
- He is an NPC, so no costume change
- Wasp
- Captain Marvel Janet.
- Classic (red)
- Confirmed as DLC
- Ultimate
- Unstoppable Wasp (Nadia Pym)
- Uncanny Avengers.
- Star-Lord
- Classic (blue and gold)
- Confirmed as DLC
- Classic (blue and gold)
- Gamora
- Classic ("fish scales" costume)
- Black Vortex
- She got the costume she wore in Annihilation and the 2008 Guardians of the Galaxy series
- Drax
- Classic (with the cape)
- Confirmed as DLC
- MCU (gray)
- Confirmed as palette swap
- Classic (with the cape)
- Rocket Raccoon/Groot
- Classic (blue coat costume)
- Confirmed as DLC; Groot also gets his own coat
- Classic (blue coat costume)
- Crystal
- West Coast Avengers (leather jacket)
- Confirmed as DLC
- All-New Inhumans (the short haired one)
- West Coast Avengers (leather jacket)
- Ms. Marvel
- Kamala Kang
- Agent Khan
- Mystic Marvel/Weirdworld Kamala
- She got the civvie outfit seen on the cover of her #1 issue as DLC
- Wolverine
- Classic (brown)
- Confirmed as palette swap
- Patch
- Leatherfang
- '90s
- Astonishing
- X-Force
- Ultimate
- Casual
- Old Man Logan
- Confirmed as DLC.
- Poison
- Classic (brown)
- Storm
- '90s (Jim Lee era)
- Biker ('80s look)
- Mohawk Storm
- Confirmed as DLC.
- Ultimate
- X-Men Red
- Nightcrawler
- Age of Apocalypse
- House of M
- Confirmed as DLC.
- Psylocke
- Original (Caucasian)
- X-Force
- House of M
- Confirmed as DLC.
- Fresh Start costume
- Beast
- Original costume
- Dark Beast
- Feline mutation
- X-Factor costume
- Black Vortex costume
- All New X-Men costume
- He is an NPC, so no costume change
- Deadpool
- Secret Agent Deadpool
- X-Force
- Confirmed.
- Cablepool
- Ultimate
- Chef
- Confirmed as pre-order bonus and later DLC
- He also got his unmasked costume from BattleOfTheAtom; thus Deadpool is the only character in the game with three different costumes
- Magneto
- Ultimate
- House Of M
- Marvel Now! (the white and black costume)
- Confirmed as DLC
- Iron Fist
- Post-Civil War
- Classic
- Daredevil costume
- Orson Randall
- Daredevil
- Original (yellow costume)
- Beta (the original Netflix clothes)
- Confirmed as DLC
- Disciple of Doctor Strange
- Elektra
- MCU
- S.H.I.E.L.D. Agent
- She got her Ultimate costume
- Spider-Man (Peter Parker)
- Scarlet Spider
- Noir
- Classic
- All-New, All-Different Marvel
- Ultimate
- Symbiote
- Confirmed as DLC
- Spider-Armor Mk. 1
- Confirmed as palette swap
- Bombastic Bag-Man
- Future Foundation
- Peter Parker
- 2099
- Iron Spider
- Captain Universe
- Spider-Man (PS4)
- Arachknight
- Poison Spider-Man
- Spider-Gwen
- Gwenom
- Confirmed as DLC.
- Charlotte Morales-Stacy/Spider-Girl from Earth-8
- Spider-Woman/Gwen Stacy from Earth-617
- Gwen's Wrestler outfit.
- Gwenom
- Spider-Man (Miles Morales)
- Merchandise 1 (Spider-Man Annual 2018 suit)
- Merchandise 2 (beta Into the Spider-Verse suit)
- Spider-Verse (hoodie costume from the movie)
- Confirmed as DLC.
- Max Morales-Stacy.
- Shadow-Spider/Weirdworld Miles.
- Venom
- 90s (blue coloration)
- Confirmed as palette swap.
- Anti-Venom
- Confirmed as DLC.
- Toxin
- Angelo Fortunato Venom
- Mac Gargan Venom
- Flash Thompson Venom
- Agent of the Cosmos Venom
- Lee Price Venom
- Venom 2099
- Hydra Venom
- Confirmed as palette swap for Anti-Venom
- Ancient/Corrupted Venom
- Magic Venom
- Ultimate Venom (with or without Chest Insignia)
- Venompool
- 90s (blue coloration)
- Doctor Strange
- Fear Itself
- 1602
- Trench Coat
- Illuminati
- Classic
- He got the early 70s "Blue Mage" costume as DLC
- Ghost Rider
- Robbie Reyes
- Ghost Rider 2099
- Cosmic Ghost Rider
- Undead G-Man
- Danny Ketch
- Carter Slade
- He got his Ghost Racers costume as DLC
- Elsa Bloodstone
- Nextwave coat
- She got her Marvel Zombies costume as DLC
- Nextwave coat
- The Punisher
- Frankencastle
- Thunderbolts
- Iron Punisher
- He got an original, Age of Apocalypse-inspired costume as DLC
- Cyclops
- Original costume
- Classic costume
- 90s costume
- Uncanny X-Men costume
- Eve of Destruction costume
- New X-Men costume
- X-Factor costume
- Astonishing X-Men costume<!—this is the John Cassaday design—>
- Confirmed as DLC.
- Revolutionary costume
- Phoenix Five costume
- Confirmed as palette swap for his Astonishing costume
- All New X-Men costume
- Symbiote
- Age of Apocalypse costume
- Ultimate
- Colossus
- Classic
- Age of Apocalypse costume
- Confirmed as DLC.
- Acolyte of Magneto costume
- Marvel NOW! costume
- Juggernaut
- Phoenix Five costume
- Ultimate
- Phoenix
- 1970s Marvel Girl costume
- Confirmed as DLC
- Classic Marvel Girl
- X-Men Gold costume
- New X-Men costume
- Dark Phoenix
- Confirmed as DLC.
- All New X-Men costume
- Symbiote Marvel Girl
- Poison Marvel Girl
- Rachel Grey
- Ultimate
- 1970s Marvel Girl costume
- Iceman
- Original snowman look
- Age of Apocalypse look
- All New X-Men costume
- Confirmed as DLC
- Symbiote
- Ultimate
- Gambit
- X-Men Blue costume
- Thieves Guild costume
- X-Factor costume
- Age of X costume
- The End costume
- He got his Age of Apocalypse costume as DLC
- Cable
- New Mutants costumes
- Confirmed as DLC (it's the original Rob Liefeld design)
- Marvel Now X-Force costume
- Split Second costume
- X-Man
- Uncanny X-Men costume
- X-Cutioner's Song costume
- Marvel Now X-Force costume
- Second Coming costume
- He does not appear in the game.
- That didn't age well.
- New Mutants costumes
- Temporarily Jossed at launch: with the exception of Deadpool's chef costume, the costumes are simple Palette Swaps of the default looks that serve as Mythology Gags to different appearances. However, real alternate costumes are coming for free sometime around early 2020.
In Ultimate Alliance 2, Jean Grey is fully playable while Nightcrawler is nowhere to be found, implying that the ending where Nightcrawler died and the X-Men disband forever is canonical. However, for Ultimate Alliance 3, Nightcrawler is revealed to be fully playable and alive, with the X-Men still together as a team, while as of this edit Jean Grey has not. While the game already likely takes place in an Alternate Continuity from the others, Nightcrawler's presence could mean this game takes place in a specific continuity where a Broad Strokes version of the first game's events have occurred, but with Jean Grey being the one who dies... and in this game, she's now ready to come back as Dark Phoenix.
- Jossed. Phoenix — Dark or otherwise — is not in the game.
- Not anymore, as Phoenix was confirmed for the X-Men DLC.
- Even so, she only appears in a side story, rather than a full-fledged campaign.
- Not anymore, as Phoenix was confirmed for the X-Men DLC.
- Hawkeye: Chris Cox, Troy Baker, Matthew Mercer, or Christopher Corey Smith
- Chris Cox confirmed.
- Black Widow: Vanessa Marshall or Laura Bailey
- Laura Bailey confirmed.
- Falcon: Bumper Robinson
- Confirmed.
- Captain Marvel: Jennifer Hale, Grey Griffin, or April Stewart
- Jossed, Erica Lindbeck voiced her instead.
- Wasp: Colleen O'Shaughnessey
- Jossed, Kari Wahlgren voiced her instead.
- Doctor Strange: James Horan or Liam O'Brien
- Liam O'Brien Confirmed.
- Star-Lord: Chris Cox, Will Friedle, or Scott Porter
- Scott Porter confirmed.
- Psylocke: April Stewart
- Jossed, Erica Lindbeck voiced her instead.
- Scarlet Witch: Kate Higgins
- Confirmed.
- Spider-Gwen: Laura Bailey
- Jossed Allegra Clark voiced her instead.
- Venom: Ben Diskin or Daran Norris
- Jossed, Steve Blum voiced him instead.
- Crystal: Stephanie Sheh
- Jossed, Mary Faber voiced her instead.
- Luke Cage: Greg Eagles or James C. Mathis III
- James C. Mathis III confirmed.
- X-Men: Cyclops (already in the game as an NPC), Colossus (ditto), Iceman, Gambit, Jean Grey, Quicksilver (as Scarlet Witch was scanned as a mutant in a cutscene, most likely this will justify Quicksilver's involvement if he's included), Mystique and Juggernaut (NPCs and boss characters).
- Cyclops and Colossus are coming in a free update.
- Iceman, Gambit, and Phoenix are included in the X-Men DLC pack, along with Cable.
- Marvel Knights: Shang-Chi (movie in the works), Blade (fan favorite from the previous games), Cloak and Dagger, The Punisher, Moon Knight, Man-Thing, or Nick Fury.
- Blade, Punisher, and Moon Knight have all been confirmed, along with Morbius.
- Fantastic Four: Mr. Fantastic, Invisible Woman, Human Torch, The Thing, Doctor Doom, She-Hulk, Namor, and Silver Surfer.
- Spider-Man, Hulk, Ghost Rider, and Wolverine could get outfits based on the New Fantastic Four if DLC costumes are a thing.
- Crystal could get her FF outfit as well, while we're at it.
- Spider-Man, Hulk, Ghost Rider, and Wolverine could get outfits based on the New Fantastic Four if DLC costumes are a thing.
- Promoted to Playable DLC (Free or otherwise): The Vision (He did join the mission in the X-Mansion during cutscenes), Ant-Man, Beast, Jessica Jones (she may complete her business with her client quick enough to join up), Winter Soldier
- All four main members of the FF and Doom are included in the DLC pack. The others either do not appear, do not get new costumes, or remain as NPCs.
- Jossed. There's no special dialogue this time around (although they do converse, it isn't in cutscenes, but in Deadpool's own file written by Rocket, which he hijacks - so, Nolan doesn't get to talk to himself again).