Madelaine Petsch
Before her Riverdale days, this starlet was first seen on the silver screen in 2015, playing "Current Girl #2" in The Hive. The actress and YouTuber made a brief appearance in the sci-fi horror film, which had a limited release. Only a few months later, Petsch was cast as Cheryl Blossom, and the rest is history.
Jon Stewart
One year before Jon Stewart took over The Daily Show, Jon Stewart debuted on the big screen in the sci-fi horror film The Faculty (1998). Stewart played Edward Furlong, a high school science teacher who meets a gruesome at the hands of his student. Rotten Tomatoes hailed the film a "rip-off of other sci-fi thrillers."