Keith Carradine was 20 in McCabe & Mrs. Miller when he played the character 'Cowboy'.
That was over 53 years ago in 1971.
This was his first recorded movie acting credit (although may not technically be his first actual acting role).
Today he is 74, and has starred in 112 movies in total, 109 of those since McCabe & Mrs. Miller was released.
In McCabe & Mrs. Miller, I think Keith Carradine looks: