Mark Margolis was 35 in The Opening of Misty Beethoven when he played the character 'Unhappy Guy on Plane (uncredited)'.
That was over 48 years ago in 1976.
This was his first recorded movie acting credit (although may not technically be his first actual acting role).
Today he is 84, and has starred in 85 movies in total, 85 of those since The Opening of Misty Beethoven was released.
In The Opening of Misty Beethoven, I think Mark Margolis looks: