Holly should be about 7 or 8 in season five, based on the show’s canonical timeline. Instead, she is portrayed by 14-year-old Nell Fisher.
Holly was presumably recast to an older age so she could be more involved in the show’s horror elements and action sequences. Now that Vecna has set his Hawkins-destroying plan in motion, everyone in town is in danger, even those who never knew the Upside Down existed. In a season five teaser clip, Holly and her mother are shown coming face-to-face with a Demogorgon for the first time.
In fact, Matt Duffer told SFX that Holly is a “centerpiece” in season five.
“Once you see the full season, you’ll have a better understanding of why it was so important to add her to the cast,” Duffer said, via GamesRadar.
“One of the reasons was, we just wanted to recapture some of the feeling of season one, and some of that you can’t recapture unless you have kids, because our kids are not kids anymore. They’re not close to being kids anymore,” he continued. “So it was really fun to add Holly and her classmates into the show, because it allowed us to recapture some of that feeling.”
