Reese's first major credit was the film The Man in the Moon (1991) when she was 14 years old. It wasn't until 1998–99 when she hit it big with Pleasantville, Election, and Cruel Intentions. Since then, of course, she's had massive success both as an actor and a producer.
Sophie Marceau - 14 years old in "la boum"
and
Natalie Portman - 12 years old in Léon