It's common for roles to be recast in Hollywood, but few cases are as infamous as the one that impacted Back to the Future (1985). Before Michael J. Fox accepted the part that made him a household name, Eric Stoltz took a crack at playing Marty McFly. You don't need a time machine to see how the alternate history of the movie would have played out—just watch the video below.
Director Robert Zemeckis wanted to cast Fox from the beginning, but the young actor was busy shooting Family Ties. Despite feeling that Fox was the best man for the part, he settled for Stoltz and commenced production in 1984. A month into principal photography, the director finally admitted to himself what he'd long suspected: The movie didn't work without Fox as Marty.
Stoltz was let go at the Puente Hills Mall—a.k.a. the Twin Pines Mall—after shooting a few scenes that conveniently didn't feature his face. Fox arrived on set a few days later. He had to split his time between filming Back to the Future and Family Ties, which led to him only getting a few hours of sleep each night, but his grueling schedule didn't hurt his performance. The movie had the missing element it needed, and it went on to become one of the biggest hits of the 1980s.
Unlike most recasting situations, Stoltz wasn't given the boot quickly. He was Marty McFly for a third of the film's planned three-month shoot, which resulted in a lot of expensive footage the filmmakers were unable to use. Many of the scenes he shot ended up being identical to the final cut, with Fox's face instead of Stoltz's being the only difference. After watching the comparison of the two Marty McFlys, check out more facts about the making of Back to the Future.