It features an ensemble cast including Pedro Pascal, Vanessa Kirby, Joseph Quinn, and Ebon Moss-Bachrach as the titular team, alongside Ralph Ineson, Julia Garner, Paul Walter Hauser, John Malkovich, Natasha Lyonne, and Sarah Niles.

[20] The basis of Grahame-Smith's screenplay came from a separate script that Carter Blanchard had written as an adaptation of the children's book Kindergarten Heroes by Mark Millar.

[32][33] Grant Curtis and Nick Pepin were producing the new Fantastic Four film by the next month after working on the Marvel Studios miniseries Moon Knight (2022).

[34] John Krasinski portrays Reed Richards / Mister Fantastic in the MCU film Doctor Strange in the Multiverse of Madness (2022).

Krasinski had been a popular suggestion for the role among fans for some time, and rumors that he had been cast as Reed had especially circulated since confirmation of the new film's development.

[35] Marvel Studios was searching for a new director by June 2022 and were not close to shortening their list of candidates, which reportedly included some high-profile filmmakers.

Feige added that the studio had "set a very high bar for ourselves" in wanting to live up to the group's long history in the comic books going back to 1961.

[43] Deadline Hollywood felt Shakman was the person to beat given his familiarity with Feige after directing the Marvel Studios miniseries WandaVision (2021).

[50] The following month, Shakman explained that he chose to work on Fantastic Four because he did not want to pass up the opportunity and was excited by the film's focus on family, optimism, and technology.

Borys Kit of The Hollywood Reporter felt Friedman's hiring indicated a possible tonal shift because he had written many science fiction projects while Kaplan and Springer were known more for comedy.

[63] Prior to the start of the 2023 SAG-AFTRA strike in July, Marvel Studios held screen tests for the role of Reed with several actors, including Christopher Abbott and Jamie Dornan, which Sneider said "did not go very well".

[60] In August, Ebon Moss-Bachrach was offered the role of Ben Grimm / The Thing,[5] after playing Micro in the first season of the Marvel Television series The Punisher (2017).

[67] Sneider reported that Marvel Studios was looking at Vanessa Kirby for the role of Sue,[49] who was expected to be the film's lead character,[60] and Joseph Quinn for her brother Johnny Storm / Human Torch.

[49] Shakman confirmed in October 2023 that they planned to start filming in early 2024 at Pinewood Studios in London, and said the cast would be announced once the SAG-AFTRA strike ended.

He said during the strikes they were able to work on the film's production design and early tests of the visual effects for translating the team's abilities from comic art to the screen.

[72] Following the conclusion of the actors' strike in November, Pascal entered talks to portray Reed and was negotiating his schedule for the film around his other commitments.

Marvel Studios was expected to make offers for the other leading roles soon after, having waited because they deemed it essential to find the actor for Reed first.

[78] On February 14, Marvel Studios released a Valentine's Day–themed announcement that confirmed the casting of Pedro Pascal as Reed Richards / Mister Fantastic, Vanessa Kirby as Sue Storm / Invisible Woman, Joseph Quinn as Johnny Storm / Human Torch, and Ebon Moss-Bachrach as Ben Grimm / The Thing.

[2] The announcement's promotional art includes the December 13, 1963, issue of Life magazine with Lyndon B. Johnson on the cover and uses a new logo style with a "certain throwback tone and sense of aesthetics", indicating that the film is set during the 1960s like the first Fantastic Four comic books.

Shakman stated, "I really wanted to take all of that great stuff from Apollo 11 and just imagine that instead of Neil Armstrong and Buzz Aldrin, it was the Storms and Ben Grimm and Reed Richards heading off into space".

[88] Also in February, Sneider reported that Bardem was the studio's top choice for Galactus, that they had begun meeting with actors for Silver Surfer, and that Doctor Doom would be cast during filming,[57] while Eric Pearson was revealed to have been "quietly hired" to polish the script.

[91] Justin Kroll of Deadline Hollywood reported that the role of Galactus was open, with no actors holding an offer or being in talks for the character.

[94] Malkovich had previously been approached to appear in Marvel films, but had declined because he felt the pay being offered was not equal to the work involved.

[99] Sneider reported that Downey, who previously portrayed Tony Stark / Iron Man in the MCU from 2008 to 2019, would be introduced as Doom in a post-credits scene at the end of First Steps.

Mike Roe of TheWrap called the theme "a jaunty vibe" that "blends a dreamy sense with future-looking heroic optimism, along with elements that echo the sounds you might expect from a film featuring, say, a space launch".

[6] Shakman explained that the teaser reel featured pre-filming footage combined with pre-visualizations and animatics that were created during the film's development.

Vulture's Jesse David Fox noted a stock sound effect used for the children's laughter, wondering if it was an intentional indication of something or if the footage had just been rushed.

[121] Discussing the full teaser, Ben Travis at Empire felt the film was "on the right track", appreciating the tone and style as well as different references to the comics.

[124][125][88] The teaser was viewed 202 million times in its first 24 hours, the third-best for a Marvel Studios trailer after those for Deadpool & Wolverine (365M) and Spider-Man: No Way Home (2021) (355M).

[127] One of these was criticized by some who believed it was created with artificial intelligence (AI), pointing to a woman's face seemingly being used multiple times and hands that appear to have the wrong number of fingers.