I know a few: Brad Pitt, Channing Tatum, Kirsten Dunst, Renée Zellweger. There are more actors & actresses who were extras prior to reaching stardom or becoming famous. Not all are obvious unless you knew what they looked like when they’re younger or looked via IMDb. I’ve spotted Bruce Willis as an extra in two movies: The First Deadly Sin starring Frank Sinatra in an uncredited role as “man entering diner” & The Verdict starring Paul Newman as an courtroom observer (uncredited) before he became famous in Die Hard.
penguinz0 in The Hunger Games, before that no one really knew him.
I don’t really watch his content a lot, but i always assumed that was some kind of inside joke when he mentioned it. That’s pretty funny
The joke is that he was cast as an extra in a crowd for the fourth(?) hunger games movie, but his scene got cut.
He turned it into an inside joke that he was just “too good” of an actor and would have taken attention away from Jennifer Lawrence.
Edit: worth mentioning that he was cast because he just happened to be in the area at the time of filming. Not because he was a niche internet celebrity