There's a pretty substantial quantity of What Could Have Been regarding Marvel Studios and Disney's incredibly successful, multi-billion dollar film franchise. The various elements related to the production of the movies set within the Marvel Cinematic Universe is absolutely astonishing.
For entries on released films and TV series, check Iron Man, The Incredible Hulk, Iron Man 2, Thor, Captain America: The First Avenger, The Avengers, Iron Man 3, Thor: The Dark World, Captain America: The Winter Soldier, Guardians Of The Galaxy, Avengers: Age of Ultron, Ant-Man, Captain America: Civil War, Doctor Strange, Guardians of the Galaxy Vol. 2, Spider-Man: Homecoming, Thor: Ragnarok, Black Panther, Avengers: Infinity War, Ant-Man and the Wasp, Captain Marvel, Avengers: Endgame, Spider-Man: Far From Home, WandaVision, The Falcon and the Winter Soldier, Loki, Black Widow, What If, Shang-Chi and the Legend of the Ten Rings, Eternals, Hawkeye, Spider-Man: No Way Home, Moon Knight, Doctor Strange in the Multiverse of Madness, Ms Marvel, Thor: Love and Thunder, She-Hulk: Attorney at Law and Black Panther: Wakanda Forever.
And for entries on one-shots and Marvel Television series set in the MCU, check Agents of S.H.I.E.L.D., All Hail the King, Agent Carter, Daredevil, Jessica Jones, Luke Cage, Iron Fist, The Defenders, Inhumans, The Punisher, Runaways, and Cloak And Dagger.
- Way back when Marvel announced their Phase One film slate in 2006, a solo Nick Fury film written by Andrew Marlowe (Air Force One, End of Days, Hollow Man) was one of the titles included. Nothing ever came of this, and Fury instead ended up appearing across the MCU as the major connective force between the movies. Eventually, Marvel Studios announced in 2021 that Fury would get a Disney+ series alongside Talos from Captain Marvel in the form of Secret Invasion.
- A Runaways film written by Drew Pearce was in the works for Phase 2, and got far enough along in production that a casting call was released (which drew flack for allegedly whitewashing Nico Minoru, though Marvel claims this was a misunderstanding), and Keke Palmer was approached for a role. The film was shelved indefinitely after the massive success of The Avengers caused Marvel to rethink its plans for future movies, and lead to the creation of Runaways on Hulu.
- Black Panther, Captain Marvel, Nick Fury, and Loki were all considered as possible Marvel One-Shots, but were ultimately rejected. The former three because Marvel felt they couldn't be done justice given the short length, and the latter because the studio thought the required special effects budget would have been cost-prohibitive. The former two ultimately got their own movies, and Loki his own Disney+ series.
- Daredevil began as a pitch for a movie reboot in the MCU. It was determined that while the idea was too low stakes and low budget to work as a film, it was the perfect fit for Marvel's burgeoning line of Netflix shows.
- When Fox still had the Daredevil rights, Kevin Feige offered them an extension in exchange for Fox returning Galactus and the Silver Surfer. This means there's an alternate timeline somewhere where the Netflix Daredevil show never happened, but Marvel got to use Galactus and the Surfer in Guardians of the Galaxy, Thor: Ragnarok, Infinity War, Captain Marvel, Endgame, and Eternals.
- Doctor Mordrid was going to be a Doctor Strange movie, but the Doctor Strange license expired.
- In a case of "what could not have been", Marvel made it clear that after New Line Cinema's Blade license expired, that there was no intention of him joining the MCU. Most likely, it was due to his Darker and Edgier nature and ties to the supernatural being an odd fit at the time. Then, after many years of fan requests, the world of the MCU itself being better established, and the MCU becoming such a Cash-Cow Franchise, a proper Blade reboot was announced for MCU Phase 5 with Mahershala Ali in the lead role.
- The creators of the Underworld franchise proposed a crossover with Marvel's Blade, presumably with Wesley Snipes reprising his role. Marvel Studios passed due to wanting to have a clean slate to reintroduce Blade at some point in the future.
- An Inhumans movie was initially scheduled for Phase 3, with a tentative November 2018 release date, which was later pushed back to July 2019. After Ike Perlmutter (who had championed the project despite a lack of interest from Kevin Feige) was ousted from Marvel Studios, the film was pulled from the Phase 3 line-up altogether, with a live-action TV show being ordered by ABC instead.
- Marvel's initial choice for Nick Fury was George Clooney, not Samuel L Jackson. Although Clooney's first superhero outing was an Old Shame for him, what caused Clooney to reject the role was the rather violent Marvel Fury (MAX) series. As such, Marvel went to Jackson, who had let them use his likeness for the Ultimate version of Nick Fury in return for being able to portray him in a film at a later point.
- Back in 1979, Marvel planned to release what effectively would've been the first Avengers movie, long before the Marvel Cinematic Universe was a concept. However, the Avengers (and Spider-Man) were side-characters for Dazzler, a disco-theme mutant. Buckle up, this gets wild. As part of a cross-promotion idea between Marvel and Casablanca Records, they envisioned Dazzler as a comic book hero whose's "secret identity" of a pop singer would be an actual singer in the real world. This idea evolved into an animated special and then a full-blown movie pitch, where Dazzler would join with the Avengers and Spider-Man were flung into the future to fight super-powered versions of KISS, Cher, Donna Summer and The Village People. Other weirdness included Robin Williams playing the main love interest and Rodney Dangerfield playing three lawyers who are the personification of an Eldritch Abomination. Both the film deal and record deal fell through, leaving Dazzler as a comic book character alone, and delaying the first appearance of the Avengers in a film by 33 years.
- Plans for a Luke Cage movie had been kicking around for years. Quentin Tarantino was once set to direct one after Reservoir Dogs starring Laurence Fishburne, but abandoned it due to studio insistence that Wesley Snipes be chosen instead. Columbia Pictures started development in 2003, with a screenplay penned by Ben Ramsey, Avi Arad serving as producer and John Singleton directing. Jamie Foxx and Tyrese Gibson were considered for the lead role, while Dwayne Johnson and Idris Elba expressed interest in playing Luke Cage.
- There were plans for an Iron Fist movie since 2000 starring Ray Park with a script by John Turman and co-financed by Artisan Entertainment. Kirk Wong signed to direct in July 2001, with filming set for late 2001/early 2002. It nearly went into pre-production in March 2002. Wong left the project in April 2002. By August 2002, pre-production had started. Filming was pushed back to late 2002 and then to late 2003. In March 2003, Marvel announced a 2004 release date. In April 2003, Steve Carr entered negotiations to direct. In November 2003, the release date was moved to 2006. In March 2007, Carr placed the film on hold due to scheduling conflicts.
- Plans for a Shang-Chi movie or television series date as far back as the 1980s with Stan Lee approaching Brandon Lee for the role. Given that Shang-Chi is often considered to be an homage to Brandon's father, this seemed like an ideal casting. Unfortunately the plans fell through after Brandon's untimely death in 1993. In 2001 Stephen Norrington signed on to direct a Shang-Chi movie titled The Hands of Shang-Chi for DreamWorks. In 2003 Yuen Woo-Ping replaced Norrington as director and Ang Lee joined as a producer in 2004, but nothing materialized after that and the rights to the character reverted back to Marvel.
- A planned adaptation of New Warriors for Freeform would've involved Night Thrasher, Microbe, Debrii, and Speedball, as well as Squirrel Girl and Great Lakes Avengers mainstay Mr. Immortal alongside them. But Freeform passed on it and no one else picked it up. The only thing left of this proposed series was the casting of Milana Vayntrub as Squirrel Girl, which was carried over to Marvel Rising. An older version of Mr. Immortal (played by David Pasquesi) would eventually appear in She-Hulk: Attorney at Law.
- During the buildup to the first Avengers movie, Marvel considered shooting the rest of their projects on 3D cameras. However, after shooting with them proved to be a nightmare for Thor's post-credit scene (as well as Stellan Skarsgård's discomfort with them), this was ultimately dropped.
- Helstrom was originally planned to be part of the MCU but the changing of the guard at Marvel Television caused this series to instead be a completely standalone Marvel Comics adaptation with no official connections to the universe, as confirmed by showrunner Paul Zbyszewski. The continuity that the series is set in was unofficially dubbed Earth-TRN836, rather than the MCU's Earth-199999.
- James Gunn pitched a Guardians of the Galaxy spinoff revolving around Drax and Mantis, but nothing came of it.
- Olivia Wilde and Jamie Babbit were approached to direct the movie before Nia DaCosta was hired. Wilde was previously offered the role of Gamora in Guardians of the Galaxy, and would eventually go on to helm a Spider-Woman film set within Sony's Spider-Man Universe.
- The project was initially revealed as Captain Marvel 2 during the Disney Investor Day 2020 presentation. The film's final title was established in The Marvels in a promotional video posted on May 3, 2021, alluding to the involvement of other characters with the "Marvel" codename, most notably Kamala Khan and Monica Rambeau.
- James Gunn was interested in directing a movie focusing on the team, which Kevin Feige claimed was a possibility should Guardians of the Galaxy do well enough at the box office. The surprise success of Guardians led to Marvel quickly announcing a sequel, which resulted in Thunderbolts being relegated to Development Hell. When the film resurfaced with a 2024 release date, Gunn had already stated his intentions on finishing his tenure at Marvel Studios with Guardians of the Galaxy Vol. 3, and so it was ultimately Jake Schreier who was chosen to direct it.
- William Hurt passed away two years earlier, or else he could have possibly been featured in the film reprising his role as Thaddeus Ross again. He would be recast with Harrison Ford.
- Wesley Snipes, who previously played the titular character in the Blade Trilogy, was approached by Marvel Studios in 2015 to reprise his role in the Marvel Cinematic Universe despite that Snipes' films aren't canon within the MCU. However, Mahershala Ali was ultimately cast in the role, with Snipes' approval.
- The film was originally tentatively planned as a TV show, and so Mahershala Ali was informed back when he appeared as Cottonmouth in Luke Cage, but it took a couple of years for Marvel Studios to reevaluate the idea and opted to bring back Blade in a film.
- Bassam Tariq was originally attached to direct this film, but he was let go sometime in 2022 due to scheduling issues.
- Michael Matthews and Reid Carolin had discussions to direct the film before Matt Shakman was hired.
- Jon Watts was originally selected to helm the movie, but dropped out of production as he wished to take a break from comic book movies after directing three Spider-Man films.
- Prior to this film, plans initially existed to continue the franchise under 20th Century Studios, who were planning on releasing a sequel to Fantastic Four (2015), and potentially crossing it over with their X-Men Film Series slate to established a Shared Universe. However, the disastrous box office performance and critical thrashing of the movie, combined with the drop in quarterly losses that year, led Fox to quietly scrap plans for the sequel and all crossovers with the X-Men. Moreover, the film's failure helped convince Rupert Murdoch that his studio was no longer competitive enough, and he ultimately sold it to Disney just two years later, with the deal being finalized in 2019.
- Like the Hawkeye situation, a solo War Machine Spin-Off was originally included in Don Cheadle's contract as a potential feature film. There were discussions about the film, and Cheadle's idea was to have Rhodey go rogue and become a fugitive in order to complete a forbidden and politically volatile mission that he viewed as morally right. Joe Robert Cole was hired to write the script, but the project was shelved due to potential conflicts with Shane Black's plans for Rhodey in Iron Man 3. Cole would later go on to write the Black Panther film with Ryan Coogler, while the idea of a solo War Machine vehicle would finally see the light of day years later as a Disney+ production...that is, until it was re-retooled into a movie once again in 2022.