There are not many examples but one characteristic of a great television show is whenever one of its main cast members dies in real life but does not derail the series. Jim Davis was a wonderful initial casting choice as the family patriarch. He embodied both the good qualities of his son Bobby and his bad side in son, J.R. He was the perfect ying to his tv wife Barbara Bel Geddes' yang. Jock was a stern, no-nonsense father-in-law and grandfather but also warm and loyal to his extended family when needed.
Larry Hagman was the primary face of the series. However, Davis was also instrumental making the series extremely entertaining during those first few seasons.