Clint Howard was 2 in The Courtship of Eddie's Father when he played the character 'Child Party Guest (uncredited)'.
That was over 61 years ago in 1963.
This was his first recorded movie acting credit (although may not technically be his first actual acting role).
Today he is 65, and has starred in 157 movies in total, 155 of those since The Courtship of Eddie's Father was released.
In The Courtship of Eddie's Father, I think Clint Howard looks: