Buster Keaton was 20 in The Butcher Boy when he played the character 'Buster'.
That was over 106 years ago in 1917.
This was his first recorded movie acting credit (although may not technically be his first actual acting role).
In 1966 he died aged 70, starring in 176 films in his career, 175 of those after The Butcher Boy was first released. If he were alive today he would be 127.
In The Butcher Boy, I think Buster Keaton looks: