Her
You might not have seen this actress change, but you certainly heard it. Scarlett Johanson's voice was the one associated with the automated robot but before she had the part, it was going to go to Samantha Morton. "In post is when we decided that what we did wasn’t working, and we ended up recasting with Scarlett," said the director.
The Lovely Bones
The Lovely Bones was one of the spookiest films based off of a book. It followed a young girl who was kidnapped and held underground as she planned her escape. Ryan Gosling prepared for the role of Jack Salmon, but apparently, he took things a little too far. His version of the character wasn't likable to casting, so they replaced him with Mark Wahlberg.