Development on a film based on The Flash started in the late 1980s when Warner Bros. hired comic book writer Jeph Loeb to write a screenplay, but nothing materialized from that.

[1] The project went dormant until it was brought up again following the release of Batman Begins, when writer David S. Goyer was offered a chance to write a script for either Flash or Green Lantern.

[3] He approached his Blade: Trinity co-star Ryan Reynolds for the Barry Allen role,[2] with the intention of also using Wally West as a supporting character.

[9] The Flash was later postponed to 2022, with Miller providing assistance to re-writing the script following creative differences with original directors/screenwriters John Francis Daley and Jonathan Goldstein.

[12] In August 2020, it officially confirmed that Keaton had signed on and that Ben Affleck would be reprising his role of Bruce Wayne / Batman from the DC Extended Universe.

Snyder's video feed played through a stand on a table enabling him to direct Miller and the crew, who filmed the scene on his behalf.

When finally exposed by Bruce, Barry is quick to agree to join the Justice League, due to his great desire to gain friends he could relate to.

[citation needed] In an interview before the release of the theatrical cut, Ezra Miller shared that they had practiced martial arts for two years in preparation for the role, even venturing to the Wudang Mountains in China to study Qinggong.

[19] The monks they encountered inspired some of Barry's more meditative movements as well as his running motion while entering the Speed Force to reverse time during the climax of the "Snyder Cut".

[20] Miller also looked to the mechanics of speed skaters, dancers and choreographers as well as certain animals, stating "I was also inspired by crows, cheetahs, mongooses and other fast-moving and intelligent creatures, as well as by rushing water and, of course, lightning.

Barry ventures with Wayne to meet with Prince in Gotham City, where they also encounter police commissioner James Gordon and fellow metahuman Victor Stone, also known as "Cyborg".

Upon returning to the lab, Barry charges up the Mother Box, which successfully revives Kent, though he has lost his memories and is triggered to attack the group.

Following the battle, Barry enthusiastically remains part of the team, now named the Justice League, and obtains an entry-level job with the Central City police department to his father's approval.

Following the battle, Barry enthusiastically remains part of the team and obtains an entry-level job with the Central City police department to his father's approval.

[27][28] In 2023, after helping Wayne and Prince stop a robbery orchestrated by Al Falcone's terrorist group, Barry revisits his childhood home, where he remembers his mother's murder and his father's wrongful imprisonment.

Eventually, the Speedster who originally knocked Barry out of the Speed Force returns and is revealed to be an older version of 2013-Barry, who still believes he can save his world from Zod and prevent the deaths of Bruce and Kara.

He explains the causal loop paradox that led to his own creation, but grows angry when Barry reveals his own intention to reverse his actions by letting Nora die.

In a dark potential future seen in visions by Bruce Wayne and Victor Stone, Darkseid has taken over the world after turning it into an apocalyptic wasteland and corrupted Superman into his second-in-command after killing Lois Lane.

When in the main timeline in which Barry tries to go back and allow his mother's death to occur, Dark Flash tries to kill him, though he impales his younger self instead, causing him to be erased from existence.

[34][35] In particular, Steve Persall of the Tampa Bay Times noted that "Ezra Miller's hyper-fast Flash is another sort of amusing, his fanboy spirit speaking for the audience while the CGI lightning trailing him is one of the movie's defining effects.

"[36] However, certain aspects of the character, such as an awkward-looking running motion and "forced" jokes as part of Joss Whedon's rewrites of the film, including the infamous "brunch" line and Flash falling on Wonder Woman's chest during the Gotham Harbor battle, were criticized.

[37][38] Despite his lone major film role and numerous cameos at the time, the DCEU version of Flash was praised as a better-written character than his counterpart in the Arrowverse by Erik Kain of Forbes.

[39] Ezra Miller's performance and characterization in Zack Snyder's Justice League was also well-received with critics praising Barry Allen's increased confidence and chemistry with other characters, reduced "cringe-worthy" one liners, and his more integral role in the final battle, as compared to the theatrical cut.

[38] Tom Jergensen from IGN wrote: "He remains the comic relief character and fills that role well, as he's still a green enough hero to freak out when entering the Batcave for the first time.

[41] After a series of grooming allegations and disorderly conduct arrests, Miller's participation in The Flash began to cause controversy with some fans campaigning that the role be recast.

Reportedly, Grant Gustin trended often on the social media site Twitter as a replacement due to his work with the character in the television series.

[44] Eventually, it was confirmed by Variety in October 2023 that no cast members from Zack Snyder's run of DCEU films would reprise their respective roles in the DCU, including Miller as The Flash.

[45] The plot description and characterization were adapted from Flash and Justice League (film) at the DC Extended Universe Wiki, which are available under a Creative Commons Attribution-Share Alike 3.0 license.