Drew Barrymore was 4 in Altered States when she played the character 'Margaret Jessup'.
That was over 43 years ago in 1980.
This was her first recorded movie acting credit (although may not technically be her first actual acting role).
Today she is 49, and has starred in 85 movies in total, 84 of those since Altered States was released.
In Altered States, I think Drew Barrymore looks: