Obviously we all know that Eric Stoltz filmed a large portion of Back to the Future before he was canned and Michael J. Fox was given the role. I found out today that Tim Roth turned down the role of Snape in the Harry Potter movies and decided to jump down that rabbit hole of what-ifs.
Reese Witherspoon and Jon Hamm - Gone Girl
Witherspoon produced Gone Girl and made her interest in the lead role of Amy Dunne known to director David Fincher. Fincher cast Rosamund Pike instead. As for Hamm, he was unable to get out of his Mad Men obligations and Ben Affleck played shitty husband Nick Dunne.
Emma Watson and Miles Teller - La La Land
The highly punchable face of Teller was almost cast in the Oscar-winning musical instead of Ryan Gosling. Scheduling conflicts arose with War Dogs and La La Land, and Teller was trying to get things figured out. Eventually, the production decided to move forward without Teller.
Watson lost out to Emma Stone, of course.
Jennifer Lawrence and Emily Browning - Twilight
Both of the talented actresses were considered for the lead role of Bella Swan. The role went instead to Kristen Stewart, but I think everything worked out well for all three women.
Christina Applegate - Legally Blonde
When Applegate received the script about seemingly-ditzy sorority girl Elle Woods, she was afraid to portray another blonde airhead and passed on the flick. Lucky for Reese Witherspoon, as portraying Woods allowed her to go on to bigger and better things.
Zooey Deschanel, Anne Hathaway, and Vince Vaughn - Silver Linings Playbook
Director David O. Russell originally had Deschanel and Vaughn in mind for the film that would later win Jennifer Lawrence an Oscar. After rewriting the script and losing Hathaway to creative differences, Lawrence and Bradley Cooper were cast as Tiffany and Pat.
Molly Ringwald - Pretty Woman
Ringwald doesn’t recall passing on the script that made Julia Roberts a star, but she was the choice to play Vivian. Instead, Ringwald passed and Roberts guffawed her way into America’s heart or whatever.
Emily Blunt - Peggy Carter and Black Widow
That’s right, Blunt was in the running for not one, but two roles in the highly successful Marvel Cinematic Universe. She couldn’t have known that these roles would be so very lucrative, of course, but it does make sense that the two badass roles would be offered to the Full Metal Bitch.