When Lorde became a pop sensation with her hit single "Royals" this summer, many were surprised to learn that the singer was just 16 years old, despite her mature appearance.
And of course, veteran child star Dakota Fanning and "Mad Men" actress Kiernan Shipka always seem poised and chic beyond their teenage years.
In fact, there are many stars we frequently forget are still very young. Browse our gallery below to see other celebs who are probably not as old as you think.
Chloe Grace Moretz