The X-Men go to war with the Inhumans for their mockery of them in their TV show along with Marvel's Agents of S.H.I.E.L.D.
- Inhuman Royal Family:
- Black Bolt (Anson Mount) - finds himself at odds with his fellow Illuminati member, Professor X, for stealing their roles in MCU
- Medusa (Serinda Swan)
- Karnak (Ken Leung)
- Gorgon (Eme Ikwuakor)
- Crystal (Isabelle Cornish)
- Secret Warriors: formed to aid the Inhumans fight the X-Men
- Daisy Johnson/Quake (Chloe Bennet) - goes after Deadpool for killing Phil Coulson and fights him
- Christopher Powell/Darkhawk (Tom Cruise) - ???
- Robbie Reyes/Ghost Rider (Gabriel Luna) - tries to make Daisy forget her rage at Deadpool killing Coulson, while Daisy calls him out for not stopping him for making a deal with the Spirit of Vengeance which caused the Kree blood to burn through Coulson no longer keeping him alive, though Robbie states that it was the only way to defeat Aida, ???
- Dennis Dunphy/Demolition Man (Sam Witmer) - ???
- Ben Reilly/Scarlet Spider (Tom Holland) - ???
- Professor X (Patrick Stewart) - clashes with Black Bolt for the Inhumans stealing their roles as mutants in the MCU for replacing them
- Scott Summers/Cyclops (James Marsden)
- James Howlett Logan/Wolverine (Hugh Jackman)
- Ororo Munroe/Storm (Halle Berry)
- Piotr Rasputin/Colossus (Daniel Cudmore) - finds out about Wade killing Coulson, and tries to reason with him not to provoke Daisy like that, he was also one of the mutants assembled by Magneto
- Warren Worthington III/Angel (Ben Foster) - he is one of the mutants assembled by Magneto
- Hank McCoy/Beast (Kelsey Grammer)
- Rogue (Anna Paquin) - ???
- Remy LaBeau/Gambit (Channing Tatum) - ???
- Magneto's mutants:
- Erik Lehnsherr/Magneto (Ian McKellen) - tasked by Professor X to form a group that would help them
- Wanda Maximoff/Scarlet Witch (Elizabeth Olsen) - she is Erik's daughter, ???
- Peter Maximoff/Quicksilver (Evan Peters) - he is Wanda's sister, and Erik's son, ???
- Lorna Dane/Polaris (Emma Dumont) - she is Wanda and Peter's half-sister, and Magneto's daughter, ???
- Jamie Madrox/Multiple Man (James Franco) - recruited by Magneto, ???
- Rahne Sinclair/Wolfsbane (Maisie Williams) - recruited by Magneto, ???
- Shiro Yoshida/Sunfire (Gaku Space) - recruited by Magneto, ???
- Wade Wilson/Deadpool (Ryan Reynolds) - looked up a comic issue of Secret Empire, where he killed Phil Coulson, and decides to do it anyway to provoke Quake into battling him, he is also the catalyst for the war as Professor X red his mind concerning the Inhumans stealing their role
- Vanisher (Simon Pegg) - the film's main antagonist, ???, his goal is to ???, at one scene, Deadpool asks him, “What have you done to my Brad Pitt Vanisher?”, which he replies, “???”
- Unus the Untouchable (Adam Baldwin) - the film's secondary antagonist, ???
- Fred Dukes/Blob (Kevin Durand) - the film's tertiary antagonist, ???
- Sauron (Ashley Zukerman) - the film's quaternary antagonist, ???
- Henry Peter Gyrich (John Tuturo) - ???
- Senator Kelly (Mark Strong) - ???
- Moira MacTaggart (Robin Wright Penn) - ???
- Sean Cassidy/Banshee (Caleb Landry Jones) - ???
- Phil Coulson (Clark Gregg) - his car, Lola was shot down by Deadpool, and then he was chased by him to an abandoned S.H.I.E.L.D. Facility, and he got shot in the chest by Deadpool (the same spot where Loki had stabbed him), and then left to be blown up, which provokes Quake into battling him for that
- Even for You - by Alan Silvestri of the Avengers: Infinity War soundtrack, Deadpool shooting Coulson in the chest, and having a recording of him doing it while putting gasoline on him and the whole S.H.I.E.L.D. Facility while leaving behind a lighter to throw into the gasoline to cause the place to blow up, which provokes Daisy to go after him
- Bangarang - by Skrillex, Quake and Deadpool’s battle theme
- Numb - by Linkin Park, played during Quicksilver's time motion slow when the Inhumans are facing the X-Men
- The difference from the film and comic is that it is based on the original design.
- The film is Rated G for ???