Sean Astin was 9 in Please Don't Hit Me, Mom when he played the character 'Brian Reynolds'.
That was over 43 years ago in 1981.
This was his first recorded movie acting credit (although may not technically be his first actual acting role).
Today he is 53, and has starred in 119 movies in total, 115 of those since Please Don't Hit Me, Mom was released.
In Please Don't Hit Me, Mom, I think Sean Astin looks: