A new fan theory may finally explain why Edward Norton's Hulk in The Incredible Hulk is different from Mark Ruffalo's Hulk. While MCU characters have changed actors before, the Hulk's actor change is by far the biggest example of this. While there is no official explanation, one theory (via Reddit) perfectly explains why Bruce Banner changes in the MCU after The Incredible Hulk.
Although it was intended for Edward Norton to play the Hulk and Bruce Banner in the MCU, Mark Ruffalo replaced Norton due to some behind-the-scenes conflicts. Ruffalo has portrayed the character in every other MCU appearance, becoming more associated with the character than Edward Norton ever was. The MCU has never had an in-universe explanation for this actor switch, leaving it open for speculation, but recent revelations in the MCU make some of these theories far more possible.
Related: The One Thing The Incredible Hulk Does Better Than Any MCU Movie
The MCU Phase 4 has been dabbling in the multiverse, with films like Spider-Man: No Way Home and Doctor Strange in the Multiverse of Madness bringing Marvel characters from different series into the MCU. As Loki explains, these alternate versions of characters are known as variants. Variants come from different but similar universes in which a series of events lead to massive shifts in the history of that universe. These variants do not necessarily have to be played by the same actor, with several Loki variants being portrayed by different performers. All of these recent MCU developments have led to a new theory regarding the Hulk: Edward Norton's Bruce Banner is a variant. Put simply, the events of The Incredible Hulk take place apart from the mainline MCU, in an alternate universe where the
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