Summer Glau was 21 in Sleepover when she played the character 'Ticket Girl'.
That was over 20 years ago in 2004.
This was her first recorded movie acting credit (although may not technically be her first actual acting role).
Today she is 42, and has starred in 13 movies in total, 12 of those since Sleepover was released.
In Sleepover, I think Summer Glau looks: