James Dean was 19 in Hill Number One: A Story of Faith and Inspiration when he played the character 'John'.
That was over 73 years ago in 1951.
This was his first recorded movie acting credit (although may not technically be his first actual acting role).
In 1955 he died aged just 24, starring in 32 films in his career, 30 of those after Hill Number One: A Story of Faith and Inspiration was first released. If he were alive today he would be 93.
In Hill Number One: A Story of Faith and Inspiration, I think James Dean looks: