Before Lindsay Lohan took on the role of Cady Heron in Mean Girls, she was an adorable 12-year-old in the 1998 classic, Parent Trap.
In the movie she played identical twins who, after being separated at birth, are each raised by one of their biological parents.
They (not-so randomly) find each other at summer camp, and then spend the rest of the movie trying to bring their parents back together again.
And since Lilo doesn't really have a twin, some serious CGI was used in the movie, BUT, Lindsey also needed a body double.
The girl had to look EXACTLY like Ms Lohan so that the audience thinks it's her twin when you don't see her entire face.
And that's where Erin Mackey comes in, who was a full seven years older than Lindsey. Erin is on the right in the photos with her on-screen fam:
And this is Erin now. She went on to become a major Broadway performer, has starred as Glinda in Wicked, and has also won numerous awards for her kick-ass voice.