Kirk Douglas was 28 in The Strange Love of Martha Ivers when he played the character 'Walter O'Neil'.
That was over 78 years ago in 1946.
This was his first recorded movie acting credit (although may not technically be his first actual acting role).
In 2020 he died aged 103, starring in 116 films in his career, 115 of those after The Strange Love of Martha Ivers was first released. If he were alive today he would be 107.
In The Strange Love of Martha Ivers, I think Kirk Douglas looks: