Griffin Dunne was 19 in The Other Side of the Mountain when he played the character 'Herbie Johnson'.
That was over 48 years ago in 1975.
This was his first recorded movie acting credit (although may not technically be his first actual acting role).
Today he is 68, and has starred in 66 movies in total, 64 of those since The Other Side of the Mountain was released.
In The Other Side of the Mountain, I think Griffin Dunne looks: