WARNING: The following article contains major spoilers for Dark Phoenix, in theaters now.

The finale of Dark Phoenix depicts a spectacular action sequence set on a military train, where the X-Men and Brotherhood of Mutants are held in U.S. government custody after Jean Grey loses control of her mutant powers. En route to a top-secret detention facility, the train is attacked by the shape-shifting alien D'Bari, led by Jessica Chastain's Vuk, who wants to fully absorb the Phoenix Force from Jean. The climactic battle closes out Fox's long-running franchise, but it's far from the only time the films have prominently featured a train as a prominent set piece.

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Trains and military convoys are been a curiously recurring trope in the series, with four of the previous films -- including spinoffs -- showcasing a sequence on, or with, a train or convoy. Setting the action on a moving location helps to heighten the urgency and kinetic nature; that's why it's commonly employed in Westerns. However, it's still an unusual decision for a superhero film series to repeatedly return to this particular mode of transport. Don't believe us? Here's a list of all the times trains and convoys have figured into Fox's X-Men films.

X-MEN

Released in 2000, X-Men revealed one of its major twists during an emotional moment set on a train. Manipulated by a disguised Mystique to leave Xavier's School for Gifted Youngsters over concerns about her uncontrollable abilities, Rogue boards a train, only to be intercepted and comforted by Wolverine. However, the tender moment is interrupted by the arrival of Magneto and his Brotherhood of Mutants.

Until then, the Brotherhood was pursuing Wolverine for seemingly unknown reasons, but Magneto chooses this moment to reveal that Rogue was his true target all along. As the X-Men battle the Brotherhood in the train station, Wolverine attacks Magneto, only for the Master of Magnetism to easily dispatch the hero, whose skeleton is laced with metal.

THE WOLVERINE

The action centerpiece of Wolverine's sophomore solo spinoff, 2013's The Wolverine, took place on a Japanese bullet train. Logan visited Japan looking for a means to finally die, racked with guilt over killing Jean Grey in X-Men: The Last Stand. Reuniting with an old friend from World War II, Logan successfully had his healing factor removed before becoming embroiled in a Yakuza plot.

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While still growing accustomed to living without his signature healing factor, Wolverine is forced to leap into action when the train is attacked by Yakuza. Even without his mutant ability, Logan proves a formidable opponent, using the velocity and obstacles around the train to his advantage and driving away the gang.

X-MEN: DAYS OF FUTURE PAST

Michael Fassbender as Magneto in X-Men Days of Future Past

Although the scene is less memorable than other installments of the franchise, X-Men: Days of Future Past still finds a way to sneak in a train brawl. Entering the film's final act, Magneto forms his own villainous plan: Have the Sentinels turn against their human masters, and betray Charles Xavier and Wolverine in the process.

After a confrontation with Beast in Paris, Magneto is wounded in an assassination attempt on Bolivar Trask. Escaping, he makes his way to the United States, and uses his abilities to hoist himself on to a train, and transports the Sentinels to a presentation with President Nixon.

DEADPOOL 2

While more of a convoy than a train, Deadpool 2's major action sequence involved the Merc with a Mouth leading the newly formed X-Force to raid a prison transport to protect young mutant Russell Collins from Cable. Unlike the prisoner transfer in X-Men: The Last Stand, the convoy in Deadpool 2 features interconnected vehicles not unlike a train, albeit on wheels instead of rails.

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Of course, despite warnings about the weather, Deadpool leads the team in a para drop, which results in the deaths of most of X-Force. With only Deadpool and Domino left alive, the two fight Cable in a thrilling on-road set piece while keeping the powerful mutant away from Russell.

DARK PHOENIX

Dark Phoenix trailer

As previously mentioned, the finale to Dark Phoenix takes place on a military transport train transferring the captive X-Men and Brotherhood of Mutants to government facility. The interesting thing here is that the climactic train battle was not always planned for the film.

According to filmmaker Simon Kinberg, the original ending was set in outer space against the D'Bari; a fight over the fate of Jean Grey and Phoenix Force, but was relocated to its final, theatrical setting during reshoots. Kinberg noted the change was made to keep the action grounded within the story rather than risk losing the emotional investment to sci-fi spectacle. A controversial change, perhaps, but at least a long-standing X-Men movie tradition was upheld.

Directed and written by Simon Kinberg, Dark Phoenix stars James McAvoy, Michael Fassbender, Jennifer Lawrence, Nicholas Hoult, Sophie Turner, Tye Sheridan, Alexandra Shipp, Kodi Smit-McPhee, Evan Peters and Jessica Chastain.