Reese Witherspoon was 14 in The Man in the Moon when she played the character 'Danielle "Dani" Trant'.
That was over 33 years ago in 1991.
This was her first recorded movie acting credit (although may not technically be her first actual acting role).
Today she is 48, and has starred in 61 movies in total, 56 of those since The Man in the Moon was released.
In The Man in the Moon, I think Reese Witherspoon looks: