Michael McKean was 28 in Cracking Up when he played an uncredited character.
That was over 47 years ago in 1977.
This was his first recorded movie acting credit (although may not technically be his first actual acting role).
Today he is 76, and has starred in 102 movies in total, 102 of those since Cracking Up was released.
In Cracking Up, I think Michael McKean looks: