Anne Hathaway — Katherine Heigl
Anne Hathway was offered the role in the movie, 'Knocked Up'. When the shoot had started, she was told there would be a childbirth scene. Anne didn't want to do the scene because of which she had a an argument with the director and was replaced by Katherine Heigl.
Kevin Spacey — Christopher Plummer
Kevin Spacey was accused of a scandal. Because of this Netflix kicked him out of the House of Cards T.V series, where he was playing the lead role. The director even cut all the scenes which subsites Spacey and replaced it with the new actor, Christopher Plummer.
Eric Stoltz — Michael J. Fox
We all remember the iconic movie Back to the Future. The director of the movie said that Stoltz's performance was not that appealing and lacked comedy which is why they replaced him with Michael J. Fox.
Christian Bale was first replaced with Leonardo DiCaprio and then asked to come back.
Christen Bale was approached for the title role for American Physcho. But then Leonardo Dicaprio had the attention and Christen was fired. The director of the movie, Mary Harron defended the original choice because of which she left the sets with Christen. But Leonardo's fans convinced him to back off because it will ruin his romantic character played in Titanic. And eventually, both the director of the movie and Christen Bale returned to the sets.
Natalie Portman — Claire Danes
Natalie Portman was the first choice to star alongside Leonardo for Romeo and Juliet, but while shooting the filmmakers realized that the 14-year-old actress' miniature looks caused problems. And so was replaced by Claire Danes.
Robert Downey Jr. — George Clooney
Robert Downey Jr. was the first choice to play one of the main roles in Gravity but it didn't take long to realize he wasn't suitable for the character. The film’s director, Alfonso Cuaron, "Robert is incredibly talented, but the technological aspects of the movie presented a big obstacle to his style of acting." So Downey Jr. was replaced by George Clooney.
Megan Fox — Rosie Huntington-Whiteley
Megan Fox was replaced by Rosie Huntington-Whiteley because she had a feud with the director Michael Bay. Rosie was a perfect replacement.
Nicole Kidman — Jodie Foster
Nicole was replaced by Jodie Foster, because of a knee injury she couldn't continue shooting. She had spent good 18 days on the set of the Panic Room.
Ryan Gosling — Mark Wahlberg
Ryan had to resign his role before the filming began. He did a good job of putting on weight for his character, he had his own vision of the character. But the director didn't like it and so asked him to leave. And he has replaced him with Mark Wahlberg.
Samantha Morton — Scarlett Johansson
During the post productions, the director was not satisfied with Samantha Morton's voice and so he asked Scarlett Johanson to redub.
