I am big fan of westerns and John Wayne in particular, but untill recently didn't know he was bald in his later years. He usually wore a toupee when socializing or acting, but In the documentery "John Wayne: America At All Cost", there is a scene where he is overseas with the american troops and he doesnt wear one.

https://i.pinimg.com/originals/f8/67/17/f8671737ca7dd32cf7b6461a9c4f6816.jpg