She-Hulk: Attorney At Law has featured a cavalcade of familiar faces from the likes of Wong and Hulk to Daredevil, a character fans never expected to see in the mainline MCU. Other characters from the history of the MCU appearing in projects has become very common.
Unfortunately, the precedent set by previous films has come with an expectation from fans that every film needs to have major cameos. While seeing familiar faces is always fun, it should only happen to serve the story. Because of this, Marvel has made the difficult decision to cut certain character appearances in their films. While not always a narrative choice, sometimes its other reasons, such as the actor's availability.
Iron Man (Doctor Strange in the Multiverse of Madness)
Largely believed to be true by fans leading up to the release of Doctor Strange 2, industry insiders and fans were dead set that Tom Cruise would appear as a variant version of Tony Stark, dubbed the Superior Iron Man. Of course, this didn't turn out to be true, but it was an idea Marvel toyed with.
Speaking with Rolling Stone, screenwriter Michael Waldron revealed that Tom Cruise was at one point considered for the film, noting, "I love Tom Cruise, and I said to [Marvel Studios president] Kevin [Feige] at one point, I was like, Could we get Tom Cruise’s Iron Man? I just don’t think it was ever an option, because of availability. Well, I mean, he was shooting Mission Impossible 7 and 8."
America Chavez (Spider-Man: No Way Home)
Before lockdowns changed Marvel's filming and release schedule for Phase Four projects, Spider-Man: No Way Home was initially going to release before Multiverse of Madness. Because of this, America was set to be introduced in No Way Home first.
According to TheDirect, her role was initially supposed to be similar to that of Ned's as Strange's "apprentice." Chavez also would have been the one to open the portals to Garfield and Maguire's incarnations of Spider-Man. Thanks to gorgeous concept art from Maciej Kuciara, fans can catch a glimpse of her using magic with Peter and MJ present. Interestingly, Isabela Merced was also attached to the role at the time.
Balder the Brave (Doctor Strange in the Multiverse of Madness)
Originally rumored to be playing the role that went to John Krasinski, Daniel Craig was, in fact, lined up to play Thor's brother, Balder the Brave. Funny enough, Daniel Craig was actually Marvel's top choice when casting for Thor first began in Phase One of the MCU, per SlashFilm.
Leading up to the release of the film, Balder was heavily rumored to be included in the Illuminati, only not to appear in the final film. Daniel Craig was up for the role but ultimately exited as he felt it wasn't worth potentially catching COVID for a day's worth of shooting. Recently released concept art from Darrell Warner gave viewers a chance to see what Balder would have looked like. Perhaps Craig can play the role in the future, as the design and casting are just stellar.
Red Skull (The Avengers)
With the Tesseract being of great importance in The Avengers, it would have made perfect sense for Red Skull to return in the film. After being teleported into space at the end of Captain America: The First Avenger, the next logical thing would have been to make him a pawn of Thanos as well as Loki.
Co-writer Zak Penn discussed the plans in 2012 with ComicBook, saying, "And while Loki was almost always the choice for the villain thanks to that character's long-lived role in the comics, there was some discussion of it being Red Skull. If I thought I could have gotten away with Thanos, I would have put him in there."
Loki (Avengers: Age of Ultron)
In a film that has its main plot, in addition to setting up future events leading to Phase Three, Avengers: Age of Ultron already felt overstuffed as is. Intended to be included in Thor's vision of Asgard, Tom Hiddleston was revealed to be part of the cast early in production but was ultimately cut from the film.
Explaining the choice to cut Loki, Joss Whedon remarked, via MTV, "The movie has so much. It's so filled. We didn't want it to feel overstuffed. I really wanted to have Loki in it, but I understood the decision that there were now too many voices in the chorus."
Adam Warlock (Guardians of the Galaxy Vol. 2)
Before Adam Warlock was set to make his grand MCU debut in Guardians Vol. 3, he was set to appear in the previous film in some capacity. While his cocoon makes an appearance on the Sovereign in the film's mid-credits scene, he was set to be a supporting player throughout the film.
Regarding his decision to cut Warlock, James Gunn mentioned to SlashFilm, "He was a big part of the screenplay and I realized it was one character too many. [...]I didn't want to lose Mantis and Mantis was more organically part of the movie anyway. So I decided to save him for later."
Doctor Strange (WandaVision)
Throughout the duration of WandaVision's run, the whole world united as numerous fan theories took over the internet, the biggest one being that Doctor Strange would appear in the finale to stop Wanda, setting up Multiverse of Madness.
Marvel Studios president Kevin Feige mentioned the reasoning behind the cut, saying, "Oh, it would've been so cool to see Doctor Strange. But it would have taken away from Wanda. We didn't want the end of the show to be commoditized to go to the next movie" (via SlashFilm).
Grandmaster (Thor: Love and Thunder)
Quickly becoming a fan-favorite character after his debut in Thor: Ragnarok, Taika Waititi would have done the unthinkable for Love and Thunder... killing Grandmaster. New concept art from Yujin Choo reveals Grandmaster would have shared a scene with Jane, Valkyrie and Thor, perhaps on Sakaar.
Both Peter Dinklage's Eitri and Grandmaster would have fallen victim to Gorr's vendetta against the gods, according to ComicBookMovie. Ultimately, it was for the best the scenes were cut as it gives their characters the opportunity to appear in a future film.
Hawkeye (Captain America: The Winter Soldier)
As a S.H.I.E.L.D. agent, it makes perfect sense for Hawkeye to be in this film. However, during pre-production on the film, writers Cristopher Markus and Stephen McFeely quickly found it difficult to find a place for Clint in the film.
It was ultimately decided against featuring him in the film. Speaking with CinemaBlend, Christopher Markus explained, "You’re introducing Winter Soldier. Fury’s got a bigger part in this one. It just started to seem like he was going to kind of get a crappy part. If we were going to use him, we really wanted to use him well".
Captain Marvel (Avengers: Age of Ultron)
Long rumored to have been made to appear in the final scene featuring the new Avengers at their HQ, it was made official as a bonus deleted scene exclusively released with the limited edition Infinity Saga Blu-Ray boxset revealed the filmed sequence.
For the scene, an actress hadn't even been cast, so a stand-in was used. Before Brie Larson was cast and Captain Marvel was set in the 90s, it's possible Marvel had completely different plans for the character. Unfortunately, fans will never know, considering how secretive Marvel is.