WARNING: The following contains spoilers for X-Men: Dark Phoenix, in theaters now.
The X-Men films have always made deviations from the source comics. They've tweaked the participating heroes and villains and shifted plot developments around from film to film. None of them change as much as X-Men: Dark Phoenix.
The film makes serious deviations from the original "Dark Phoenix Saga." The film changes the cast, alters the villains and completely rewrites the ending. Here are the biggest differences between X-Men: Dark Phoenix and the original "Dark Phoenix Saga."
Mystique's Role
The X-Men films introduced a uniquely relatable version of Mystique (Jennifer Lawrence). Raven became the adopted sister of Charles Xavier (Patrick Stewart). She played a more distinct role in the formation of the X-Men as a team. She eventually turned on the team and joined up with Magneto's Brotherhood, almost leading to the dark future of Days of Future Past. Eventually returning to the team Xavier formed in X-Men: Apocalypse, she became a vital member of the X-Men.
In Dark Phoenix, she's portrayed as having become a mentor to Jean. Whereas Xavier sees her potential, Mystique worries for the girl behind it. She tries to talk down Jean (Sophie Turner) when she's having trouble controlling her powers, which leads to Jean accidentally lashing out and impaling her on a piece of broken wood. Mystique in the comics is more outwardly villainous and had no role to play in the original story. The attempts to control her power didn't seriously injure any of the X-Men in the comics, although she eventually lashed out at times.
Schism
One of the biggest subplots of Dark Phoenix follows the death of Mystique. Beast (Nicolas Hoult) and Magneto (Michael Fassbender), enraged by the loss of Mystique, decide that Jean is too dangerous to live. When they arrive (alongside Selene and Red Lotus) to kill her, they're confronted by Xavier, Storm (Alexandra Shipp), Cyclops (Tye Sheridan) and Nightcrawler (Kodi Smit-McPhee). The conflict quickly breaks out into a full-blown battle, which destroys most of the city street they're on and turns public opinion against the X-Men.
There's no such battle in the comics. In the original comics, the X-Men are uniformly supportive of Jean after she's been corrupted by the Dark Phoenix. Even after she flies off into the cosmos and destroys the D'Bari world, the X-Men fight alongside her and for her. All of the team members consider their thoughts on the matter and decide that, regardless of the crime, they can't turn on Jean. There's no brief civil war between the heroes. They fully unite behind Jean.
Alien Players
Alien races end up playing important roles in both versions of the story. Both even feature the D'Bari, but their role in the story is radically different. In the newest X-Men film, the alien race comes to Earth to try and manipulate Jean. They want to claim the Phoenix power for themselves. They intend to use it to replace their destroyed homeworld by wiping out humanity and taking Earth for themselves. Their leader, Vuk (Jessica Chastain), even becomes a major corrupting influence on Jean. They're revealed to be shapeshifters, which isn't a power the species lay claim to in the comics. However, that is a major power of the Skrulls, who were rumored to be in earlier drafts of the film.
In the comics, the D'Bari only appear for a few panels before they are wiped out by Dark Phoenix consuming their local star and causing a supernova that destroys the planet. However, the Shi'Ar are prominent in the original. Enraged by the destruction of the world (and a Shi'Ar scout ship), they put Jean on trial for her crimes. Their Imperial Guard even challenges the X-Men to a trial by combat to determine her fate. They handily defeat the X-Men, leading to the climax of the original story.
The Hellfire Club
One of the biggest elements from the original "Dark Phoenix Saga" that doesn't appear in the film is the antagonistic group called the Hellfire Club. The mutant cabal appeared in X-Men: First Class and, even there, the roster of villains was different. Although Sebastian Shaw (Kevin Bacon) and Emma Frost (January Jones) were present in that film, other prominent Hellfire Club members like Donald Pierce and Harry Leland were absent. Most notably, Mastermind was nowhere to be seen, although a character with illusion powers similar to his appeared in X2: X-Men United.
In the comics, the Hellfire Club was the primary force trying to corrupt Jean. Mastermind, in particular, used his abilities to try and force Jean to fall in love with him. Jean was meant to become the Black Queen of the Hellfire Club, corrupting her into the Dark Phoenix. The D'Bari take on their role at times, appearing as an inner circle of advisers to Vuk. But, ultimately, the aliens become much more of a faceless threat than the devious Hellfire Club. While Mastermind is driven mad by Dark Phoenix, most of the Hellfire Club goes on to be consistent villains throughout future X-Men stories.
The Climax
Ultimately, both stories showcase Jean Grey being consumed by her powers and choosing to sacrifice herself to save her fellow X-Men, but each ending has a major difference regarding Jean's motivations. In Dark Phoenix, Jean fully embraces her powers. She uses them to wipe out the attacking D'Bari. She confronts Vuk, but realizes her powers are quickly wiping out the rest of the X-Men. Deciding to embrace her powers and evolve into something new, she blasts her and Vuk into space. The ensuing outpouring of energy kills Vuk, and Jean becomes one with the Phoenix Force. She then leaves the planet, still alive but in a new form.
In the original "Dark Phoenix Saga," Jean risks being consumed by the Phoenix Force when the X-Men lose her trial by combat. With only Cyclops and Jean still standing, she can feel the cosmic power overtaking her. Deciding that she'd rather die as a human instead of living as an unfeeling god, she takes matters into her own hands before her powers fully return. She activates a laser hidden on the battlefield, reducing herself to ash right in front of a pleading Cyclops. It's a tragic ending to the story, a direction that the film doesn't embrace. Instead, the X-Men franchise ends on a bittersweet note about evolution and change. Which, with the purchase of the X-Men rights by Disney, actually becomes an apt conclusion to the series.
Directed and written by Simon Kinberg, Dark Phoenix stars James McAvoy, Michael Fassbender, Jennifer Lawrence, Nicholas Holt, Sophie Turner, Tye Sheridan, Alexandra Shipp, Kodi Smit-McPhee, Evan Peters and Jessica Chastain. The film opens Friday nationwide.