Kevin McCarthy was a terrific actor. Although his leading man days didn’t last, he had a long career as a character actor.
I recall an episode of Twilight Zone in which he played a college professor who taught history , and was particularly knowledgeable about the Civil War . He was in love with a younger woman whose father was suspicious of him . The father discovers that he ( McCarthy ) was actually an officer in the Cival War and never aged . In the end I think the father shot him and while he was dying he withered away into a 100+ year old man .