Earle Hyman ( October 11 , 1926 -- November 17 , 2017 ) was an American stage , television , and film actor . Hyman is known for his role on ThunderCats as the voice of Panthro and various other characters . He also appeared on The Cosby Show as Cliff 's father , Russell Huxtable .

Question: who was the grandfather on the cosby show
Answer: Earle Hyman