Bruno Kirby was 21 in The Young Graduates when he played an uncredited character.
That was over 52 years ago in 1971.
This was his first recorded movie acting credit (although may not technically be his first actual acting role).
In 2006 he died aged just 57, starring in 41 films in his career, 40 of those after The Young Graduates was first released. If he were alive today he would be 73.
In The Young Graduates, I think Bruno Kirby looks: