That was over 18 years ago in 2004.
Today she is 36, and has starred in 39 movies in total, 35 since Mean Girls was released.
In Mean Girls, I think Amanda Seyfried looks:
Mean Girls scores 7 out of 10 on The Movie Database.
Amanda Seyfried's first acting role was as 'Karen Smith' in Mean Girls, released in 2004 when she was 18.