George McFly appeared in all three Back to the Future movies, but Crispin Glover only played the role in the original film - and here's why. Prior to starring in Robert Zemeckis' time-traveling classic, Glover had mostly appeared in a variety of TV shows in small roles, with his most notable performance was in Friday the 13th: The Final Chapter. This made Back to the Future a big role for him.
Although not the lead, Glover played a central role in Back to the Future thanks to the story. When in the past, Marty searched to find George and make sure he met Lorraine, his future wife, which required Glover to play the quirky younger version of George. But, parts of Back to the Future also took place in Marty's present and meant Glover needed to be aged up to play George in these scenes. Once Marty secured his parents falling love, he returned to the present to see that his family's life is significantly better than it was when he left.
This ending for Back to the Future, though, is part of the reason why Glover didn't return for the sequels. As discussed in the latest Screen Rant video, Glover has opened up in interviews about his disagreement with this ending. He didn't like that the McFly family was suddenly richer, and thus happier, in the end. His debates with Zemeckis fractured their working relationship, which didn't help Glover later on. When it was time for the sequels to be made, Glover believed he should be paid on equal terms with the film's other stars, and the decision was made to move on at that point.
Without Glover, Zemeckis made the decision to recast the role, but also do something a bit more. Jeffrey Weissman was selected to play George in the sequels, but Weissman doesn't look exactly like Glover. To help make the recast as unnoticeable as possible, Weissman had to wear extensive prosthetics on his face to make him look closer to Glover. Even with this aid, the two men aren't an exact match, but it did make the transition seamless enough that some viewers may not have noticed.
While Glover missed out appearing in two successful Back to the Future sequels, he has gone on to continue having success elsewhere. He was in Twister in 1989 and then played Andy Warhol in The Doors in 1991. He then joined the Charlie's Angels franchise from the early 2000s. Some of his other notable films include Like Mike, Beowolf, Alice in Wonderland, and Hot Tub Time Machine. Most recently, Clover has played Mr. World on American Gods and will return to the role in the upcoming third season.