If by public domain you mean shows that are at least 50 years old,the Andy Griffith Show is popular.Leave It to Beaver and early Bonanza episodes also qualify.
Bonanza, The Andy Griffith Show and The Beverly Hillbillies are examples of popular public domain television shows. The reason they are in the public domain is that theie copyright status was not renewed.
There are a number of popular TV shows that have fallen into the public domain. Bonanza, The Beverly Hillbillies, Petticoat Junction and the Roy Rogers Show are some of the more famous.
