While John Krasinski portrayed Earth-838's Reed Richards/Mister Fantastic in Marvel Studios' Doctor Strange in the Multiverse of Madness, comments made my director Sam Raimi seems to imply that Krasinski won't necessarily be reprising the role in the prime Marvel Cinematic Universe.
In Multiverse of Madness' official audio commentary, Raimi revealed how exactly Krasinski was cast as the leader of the Fantastic Four. "It's so funny that [Marvel Studios president Kevin Feige] cast John because the fans had a dream of who the perfect Reed Richards would be." However, the director added, "And because this is an alternate universe, I think Kevin said, 'Let's make that dream come true.' I've always really enjoyed all of his performances."
Raimi's comments about Krasinski being cast as Reed Richards because his version of the character exists "an alternate universe," and about how Feige apparently saw this fact as an opportunity to bring a popular fan-casting to life, seem to imply that the actor's turn as the character may have been a one-off. Notably, Marvel Studios is developing its own film reboot of Fantastic Four set within the MCU, though it has not been confirmed whether or not Krasinski would be appearing in that film.
In light of Raimi's comments, fans have been discussing the matter of Krasinski's potential MCU future -- or lack thereof -- on social media. Some argue that Krasinski could easily play the MCU's main version of Reed Richards in Fantastic Four. After all, in Multiverse of Madness, Benedict Cumberbatch played multiple versions of Doctor Strange from all across the multiverse. That said, others have pointed to Spider-Man: No Way Home -- which features three entirely different versions of Peter Parker, played by Tom Holland, Andrew Garfield and Tobey Maguire, respectively -- as evidence that Reed could potentially be recast.
In addition to the uncertainty regarding who will be playing Reed Richards in the upcoming film, very little is currently known about Marvel Studios' Fantastic Four. The film was announced at The Walt Disney Company's Investor Day presentation in December 2020, with No Way Home's Jon Watts attached to direct. However, Watts dropped out of the project in April 2022. Fantastic Four also currently lacks an official release date -- or even a release window, for that matter.
Krasinski is the fourth person to portray Reed Richards in live-action. Alex Hyde-White stepped into the role of Mister Fantastic for producer Roger Corman's never-officially-released 1994 film The Fantastic Four. Ioan Gruffudd later played the character in 20th Century Fox's 2005 film Fantastic Four and its 2007 sequel, Fantastic Four: Rise of the Silver Surfer. Finally, Miles Teller played Reed Richards in Fox's 2015 Fantastic Four reboot.
As Raimi mentioned, Krasinski was a popular pick by fans to portray Mister Fantastic in the MCU, with Krasinski himself expressing interest in making the fan-casting a reality. Fans finally got their wish in Multiverse of Madness, which saw Krasinski's Reed Richards as a member of the Illuminati, the premier superhero team of Earth-838. Krasinski's appearance was short-lived, however, as Mister Fantastic -- along with the rest of his team -- would soon die at the hands of Elizabeth Olsen's Scarlet Witch.
Doctor Strange in the Multiverse of Madness is currently streaming on Disney+. Marvel Studios' Fantastic Four does not currently have a theatrical release date.
Source: Doctor Strange in the Multiverse of Madness Audio Commentary, via The Direct