Roddy McDowall was 38 in Planet of the Apes when he played the character 'Cornelius'.
That was over 56 years ago in 1968.
In 1998 he died aged 70, starring in 166 films in his career, 115 of those after Planet of the Apes was first released. If he were alive today he would be 95.
In Planet of the Apes, I think Roddy McDowall looks: