Edward Norton hasn't played Mark Ruffalo took over as Bruce Banner/Hulk in a fan-favorite casting.
Marvel's fourth Disney+ series, What If...? builds on the multiversal groundwork laid by Avengers: Endgame by telling alternate history-style stories of MCU events. It is based on the general concept of the comic book series of the same name, as well as a few other points of inspiration, such as the Marvel Zombies limited series, which will be adapted in a future episode. Both the half-hour run times and the animated nature of What If...? make it less of a commitment for actors, and as such, many stars of the MCU have returned to voice their characters.
Although What If...? is technically canon in the MCU, its creative goal seems to be to shake things up outside of the constraints of a heavily serialized narrative, while also capitalizing on audiences' familiarity with said narrative. The first two episodes have already shown that an effective expression of this is characters taking on each other's roles, so it could be fun to have the Ruffalo Hulk encounter the Norton Hulk, playing with one of the MCU's most prominent recasts in a meta way. As previously mentioned, the show already features high-profile voice acting talent, so it wouldn't be a huge stretch to bring in Edward Norton, who is now only moderately less connected to the MCU than current cast .
Of course, the viability of Norton's return rests not only on narrative allowance but also on the actor's interest, if any. Unlike Terrence Howard, who was replaced by Birdman or (The Unexpected Virtue of Ignorance) even has a disdain for and a distance from superhero films in reference to this.
In the theatrical realm, Shang-Chi and the Legend of the Ten Rings, respectively. At a time when anything seems possible in of crazy casting, bringing back Norton, whose Bruce Banner had such a markedly different vibe from Ruffalo's, could be a great addition to Marvel's current antics, whether on What If...? or on the big screen.
