The Story Behind Replacing Eric Stoltz with Michael J. Fox in BACK TO THE FUTURE

Film productions in Hollywood have new issue with replacing actors in the middle of production if things aren’t working out. Sometimes it’s creative differences, sometimes it’s a bad fit, and sometimes it’s just bad luck.

Whatever the reason, looking back, the switch of actors almost always seems like the right call. Think about Eddie Murphy taking over for Sylvester Stallone in Beverly Hills Cop or Kevin Peter Hall stepping in for Jean-Claude Van Damme in Predator.

The final product just worked better. But perhaps the most famous case of all is Back to the Future, when Eric Stoltz was replaced by Michael J. Fox.

Writer Bob Gale got the idea for Back to the Future while flipping through his father’s high school yearbook. It made him wonder: Would he and his dad have been friends as teenagers? That question turned into a screenplay co-written with Robert Zemeckis.

When the time came to cast Marty McFly, they looked at casting Johnny Depp (A Nightmare on Elm Street) and Ralph Macchio (The Karate Kid), but the one actor they really wanted was Michael J. Fox. His comedic timing on Family Ties made him their ideal pick, but there was a problem. The show's producer wasn’t willing to let him go.

With Fox unavailable, the studio settled on Eric Stoltz after also strongly considering C. Thomas Howel (Red Dawn). Stoltz was coming off the film Mask and had serious dramatic chops.

Universal CEO Sidney Sheinberg backed the decision, but with one caveat: If things didn’t work out, they could reshoot with someone else. And that’s exactly what happened.

As soon as filming began, something felt off. Stoltz was a method actor, insisting on being called "Marty" on and off set. His approach was intense… too intense for a character who was supposed to be a fun-loving slacker. Lea Thompson, who played Marty’s mother, recalled:

"Eric had such an intensity. He saw drama in things. He wasn't really a comedian, and they needed a comedian. He's super-funny in real life, but he didn't approach his work like that, and they really needed somebody who had those chops."

Stoltz also took things a little too far during physical scenes. Thomas F. Wilson, who played Biff Tannen, ended up with real bruises after rehearsing their cafeteria fight. But more than that, Stoltz’s Marty just didn’t have the lighthearted charm Zemeckis and Gale envisioned.

Zemeckis said: “Eric is a really good actor, and I made the decision to put him in the movie, but it turned out that his instincts and the type of the comedy [of] the film we were doing weren’t really gelling."

Looking at the few surviving clips of his performance, you can see the difference. In one key scene where Marty realizes he’s in 1955, Stoltz plays it with purpose, running across the street with determination.

Fox, on the other hand, stumbles, bumps into a lamppost, and delivers the same moment with a perfect mix of confusion and humor. The change in energy completely alters the tone of the film.

After a month of shooting, Zemeckis, Gale, and the producers reviewed the footage and knew it wasn’t working. They went back to Sheinberg, who finally let them pursue their original choice. This time, they struck a deal. Fox could do Back to the Future as long as Family Ties remained his priority.

As you might imagine, Fox’s schedule was brutal. He filmed Family Ties during the day, then rushed to the Back to the Future set at night. He was running on fumes, but you’d never know it from his performance. His energy, charm, and comedic instincts were exactly what the movie needed.

Stoltz was still filming scenes when the decision to replace him was made. He didn’t know he was being let go until it was official. Years later, he reflected on the experience, saying:

"I think just getting through that difficult period helped me realize how freeing it really was. I went back to acting school, I moved to Europe, I did some plays in New York and I actually invested in myself in a way that was much healthier for me.

“If I had become a massive star, I don't know if I wouldn't have gone into therapy. On the other hand, I would've been exceedingly rich which would've been wonderful!"

Back to the Future became an iconic film, and Marty McFly is one of the most beloved movie characters of all time. Stoltz, meanwhile, went on to have a successful career, including a memorable turn as Lance in Pulp Fiction.

In the end, Back to the Future wouldn’t have been the same without Fox’s comedy skills, personality, and charisma.