Connery didn't think he had what it took to play Gandalf. “I never understood it,” he stated. “I read the book. I read the script. I saw the movie. I still don’t understand it.” Sir Ian McKellen's interpretation of Gandalf won him an Oscar nomination, so maybe he "got it."
Anne Hathaway, Knocked Up
Hathaway initially accepted the role of Alison Scott in the 2007 Seth Rogan and Judd Apatow rom-com. She pulled out because she was uneasy about the filmmakers using real footage of a woman giving birth to create the illusion that she was giving birth.