Early Concept Art for the movie.
- Kit Harington, Richard Madden, Jack O'Connell and Anton Yelchin read for the role of Reed Richards before Miles Teller was cast. Harington and Madden would eventually go on to portray Dane Whitman and Ikaris in Eternals respectively.
- Saoirse Ronan, Allison Williams, Emmy Rossum and Margot Robbie screen-tested for the part of Susan Storm before the casting of Kate Mara.
- Christian Cooke auditioned for the role of Ben Grimm before Jamie Bell was cast.
- Sam Riley, Eddie Redmayne, Domhnall Gleeson and Jack Huston read for the part of Victor Von Doom before the casting of Toby Kebbell.
- Tim Blake Nelson was originally playing Harvey Elder, the person who becomes Mole Man, but his role was later modified into establishing his character as a Canon Foreigner.
- Joe Carnahan, James McTeigue and David Yates were considered to direct the film before Josh Trank was hired. Yates' version of the film would've reportedly featured Adrien Brody or Jonathan Rhys Meyers as Mister Fantastic, Alice Eve as Invisible Woman and Bruce Willis as the voice of the Thing.
- Josh Trank explained
that he wanted to cast the entire Storm family with African-American actors, but was met with an Executive Veto from the studio with regards to Sue Storm, who they insisted be portrayed by a white actress. - Jeremy Slater's original script for the movie was planned to be a much more faithful adaptation, but it was rejected to save on budget - in fact, the only thing from his screenplay that made it to the finished product was a young Reed saying "Don’t blow up". The first third of the script served as the basis for the majority of the final film's story, albeit with several elements hastily fit in for the film to have a conclusion:
- In general, the Fantastic Four would have used their powers in more varied ways and would utilize a greater degree of teamwork.
- Franklin Storm was not present in the script.
- Ben and Reed teleported objects into another dimension, which would have later been found in the Negative Zone.
- Ben's status as The Big Guy was also established in more detail - essentially having the character serve as Reed's bodyguard - as a way to justify his involvement in the expedition.
- Victor would have secretly stolen Reed's research to give to Latverian spies.
- Sue and Johnny were originally both going to stay behind and use the Baxter Building's technology to help Reed, Ben, and Victor explore the Negative Zone. The expedition would have involved a portal instead of a teleporter.
- When the characters teleported into the Negative Zone, they would have found themselves inside a ruined otherworldly city with alien corpses strewn about. They would have found Galactus there (appearing as he does in the comics), who would have seemingly killed Victor with Dark Matter. Galactus would have fired the Dark Matter into the portal that Ben and Reed were using just as they escaped, affecting the two of them alongside Johnny and Sue. A Body Horror sequence similar to the one in the final film would have played out, with a noted addition of there being a scene where Sue's skin disappeared and her muscles were visible.
- A Time Skip of four years would have been implemented. While Ben still would have been used as a military weapon and Reed would still have been a fugitive, Johnny was going to have been a television star and Sue would have used her powers to help people suffering from cancer (and search for a cure for Ben's condition). During his time in hiding, Reed would have built H.E.R.B.I.E. as a Robot Buddy, alongside the Fantasti-Car. Ben also would have come to terms with his status as a monstrous-looking being.
- Latveria's government would have completed their own version of the portal using the knowledge that Victor stole. Victor would have come out of the portal as Doctor Doom, killing the military and government leaders singlehandedly and quickly conquering Latveria.
- Doctor Doom would then send shock troopers armed with futuristic weapons after Reed, who would escape with H.E.R.B.I.E. and the Fantasti-Car to warn his friends in New York.
- Harvey Elder created artificial life (the Moloids) at the Baxter Building that Sue would have feared would be weaponized. Her fears are proven correct when Doom's shock troopers arrive and activate the Dark Matter on one of the Moloids, transforming the creature into Giganto. The Moloid formula would have spilled onto Harvey Elder and he would have become the Mole Man, who would serve as a Sequel Hook to the movie.
- The team then would have met in New York to battle Giganto together, officially making them the Fantastic Four. After defeating the monster, Mister Fantastic, Invisible Woman, Thing, and Human Torch would travel to Latveria to battle Doctor Doom and his army of shock troopers.
- Doctor Doom would have been revealed to be a Composite Character with traits of the Silver Surfer, while Galactus would similarly have been a Composite Character with traits of Annihilus. After serving as Galactus's herald for four years, Doctor Doom decides that it would be better to destroy him and save the Earth by building the Ultimate Nullifier.
- The Fantastic Four would have discovered that the Doctor Doom they face was Actually a Doombot in a manner of speaking - Victor Von Doom is physically tied within the Negative Zone. The Fantastic Four ultimately defeat Doctor Doom's copy on Earth and trap Doctor Doom in the Negative Zone. The Fantastic Four warn the government of the threat of Galactus, continuing Doctor Doom's work on the Ultimate Nullifier in a way that does not threaten the rest of the world.
- The Fantastic Four make the Baxter Building their base of operations and sow the seeds of the Future Foundation by bringing in Child Prodigies and Teen Geniuses from around the world to solve the world's problems.
- Barely three weeks after the film's release, Max Landis (screenwriter for Trank's own Chronicle) revealed his own rejected script from four years prior. Aspects featured include: the team getting their powers within the first ten minutes of the film, the team splitting soon after so as to develop them separately (similar to how The Avengers handled its heroes), and Victor Von Doom being mentioned a few times before he appears near the end of the film — with The Reveal that he was Good All Along and Reed's friend and rival. For the lattermost point, Landis intended to handle Doom similar to how Sam Raimi used Harry Osborn in the Spider-Man Trilogy, and build up to a Face–Heel Turn over the course of several movies — rather than having him as the Big Bad of the first film. However, he did not specify if Doom's abilities would be depicted like in the comics or not.
- At first the Fantastic Four movie reboot was going to be set in the same universe as Fox's X-Men Film Series. Then next year, this conceptual cinematic universe was shot dead by Fox's admission.
- Rumors abounded in 2012 that Marvel Studios was offering Fox an extension to reboot Daredevil in exchange for the rights to characters associated with the Fantastic Four that belong to Marvel's cosmic universe (particularly Galactus & Silver Surfer, but it could've also included others like Uatu the Watcher, Annihilus, the Skrulls, the Badoon, etc) so they could be used for future MCU films (like Avengers: Infinity War and Guardians Of The Galaxy Vol 2.)note . Fox refused to take Marvel up on the offer note , even though there are currently no plans at Fox to use any of the aforementioned cosmic characters in either a Fantastic Four or an X-Men film. note
- The 3-D conversion that this movie was planned to have was outright canceled in order to finance the reshoots. It was even edited out of the initial poster that advertised that the movie would be shown in 3-D in the first place, although the line "in premium large-format theaters" still appears.
- Doombots were originally going to appear in the movie, although this was eventually cut from the film.
- Victor's last name was originally going to be "Domashev", and he was envisioned as a blogger with programming skills. His surname was kept the same, and any mention of him blogging is removed from the final film.
- As mentioned above, three major action sequences were cut from the film entirely.
- The Target exclusive "Photo Diary" edition of the Blu-Ray has behind-the-scenes pictures that reveal additional scenes that aren't in the movie. One image shows Johnny fighting Doom in front of a burnt-out car. This could possibly tie into another cut scene in which the Fantastic Four walk away from a destroyed Fantasticar. Another scene shows Doom's destroyed mask/face lying on the ground, presumably after the final battle.
- Had there been a sequel, Bryan Singer was reported to be the top choice to direct. Tommy Wiseau, of all people, was also interested in directing the sequel.
- Fox pushed ahead with the film's production just short of a year before the rights to the characters were to expire. Presumably, if they had not done so, the rights would have reverted back to Marvel Studios, allowing the characters to be integrated into the Marvel Cinematic Universe.
- Ironically, due to the behind-the-scenes controversies turning many viewers away from the film, the Marvel logo was used notably more prominently in advertising than in Fox's other superhero movies around this time, possibly suggesting that the studio felt the film's success depended on the audience mistaking it for an MCU film.
- Eventually subverted — Marvel would gain access to the characters over four years after the release of the movie when Disney bought the entertainment assets owned by 21st Century Fox and the deal was finalized in 2019.
- In 2017, around the same time that Legion (2017) showrunner Noah Hawley revealed that he was working on a project focused entirely on Doctor Doom, rumors surfaced that Fox was looking into doing another movie with Franklin and Valeria Richards in place of Reed and Sue, with both Johnny Storm and Ben Grimm serving as supervisors. Said reports later indicated that said screenplay was meant to be a Dolled-Up Installment of Mark Millar's Kindergarten Heroes. The kid-friendly spin-off didn't seem to go anywhere following Disney's acquisition of Fox, while Hawley's project remained in development, albeit with an uncertain future.
- Some concept art reveals that the Thing could have had an aesthetic akin to a fungus-like growth.
- If they did have a sequel, it would be filmed on a bigger budget, with the same cast but a new director (presumably Bryan Singer, as mentioned above). The film would also have had a lot of humor and plenty of action when the superhero team discovers that Doom had made a deal with Galactus to destroy Earth.
