Edward Norton

Reason Of Firing
However, that wasn't the last word on the subject, because of a report in the lead-up to Comic-Con International 2010 that Marvel planned to recast Norton for The Avengers, which would assemble all of the heroes introduced to date in a single film. That was immediately confirmed in a statement by Marvel Studios President Kevin Feige, issued from the set of Captain America: The First Avenger. "Our decision is definitely not one based on monetary factors," he wrote, in part, "but instead rooted in the need for an actor who embodies the creativity and collaborative spirit of our other talented cast members. The Avengers demands players who thrive working as part of an ensemble, as evidenced by Robert, Chris H, Chris E, Sam, Scarlett, and all of our talented casts."

Unsurprisingly, Norton's agent fired back, calling Marvel's comments “offensive,” and “a purposefully misleading, inappropriate attempt to paint our client in a negative light.”

However, Norton gave another explanation for his departure during a 2014 interview, saying he had "experienced what [he] wanted to" with the part, and he "didn't want to have an association with one thing in any way degrade [his] effectiveness as an actor in characters." While promoting his roles in Birdman and Moonrise Kingdom, Norton also explained the obligations of a mainstream franchise would clash with such work. Norton has since said he'd happily return to the MC,  and that he harbors no ill will Mark Ruffalo, who replaced him as Bruce Banner starting in 2012's The Avengers.

Character
He played Bruce Banner in the incredble Hulk and was meant to return in the avengers but was recast with Ruffalo