20 Things You Didn't Know About Gone Girl

The most crucial piece of casting in the movie was, of course, Amy Dunne herself, as was eventually played to Oscar-nominated success by the brilliant Rosamund Pike.

But for a while the part was Reese Witherspoon's for the taking, given that she initially acquired the film rights to Gillian Flynn's book in June 2012, and was set to come aboard as both producer and star.

After meeting with Fincher, however, Witherspoon decided she wasn't the right fit for Amy, though remained involved as a producer.

Afterwards, the likes of Charlize Theron, Natalie Portman, Emily Blunt, Rooney Mara, Olivia Wilde, Abbie Cornish, Jessica Chastain, and Julianne Hough were all considered to play Amy before Fincher landed on Pike.

It's easy to see how Theron, Blunt, and Chastain in particular could've made the part their own, but Pike is so note-perfect in the role that it's hard to argue with Fincher's ultimate choice.