Emily Blunt — Lost Black Widow to Scheduling

Blunt was cast as Black Widow in Iron Man 2 (2010) but had to drop out due to a contractual obligation to Fox for Gulliver's Travels — a film that bombed with $237 million against a $112 million budget. Scarlett Johansson replaced her and went on to earn an estimated $75 million from the MCU across 10 films, including a solo Black Widow movie. Blunt has said she was "contractually obligated" and clearly not happy about it. She's since built an incredible career (A Quiet Place, Oppenheimer), but the $75 million MCU ride that could have been hers haunts every "what if" list in Hollywood.