Hollywood has a history of hiring adults to play teens in movies and TV shows, which in some ways makes sense—casting a high schooler is kind of tricky since most high schoolers tend to be...in high school.

But there's a difference between hiring a 20-year-old to play someone who's 18 and hiring a 30-year-old to play someone who's 16. And some casting directors have definitely pushed the limits when it comes to casting actors who are over a decade older than their on-screen alter egos. As it turns out, the "teenagers" in a bunch of your favorite movies and TV shows were well into adulthood when they were cast. I'm talking hits like Friday Night Lights, The O.C., Outer Banks, Sex Education, Mean Girls, Grease, Riverdale, Little Women, Derry Girls, and even Pretty Little Liars.