This man is the husband of Susan's Mother. He is the father of Susan and the father-in-law of Wyatt. He is the maternal grandfather of Penny, Randall, as well as Penny And Randall's Sister. He is the ex-maternal grandfather-in-law of Zack Johnson and the current maternal grandfather-in-law of Leonard Hofstadter and Penny And Randall's Brother-in-law (Sister's Husband). He is a great-grandfather to Penny's Nephew. Penny And Randall's Cousin may be his possible grandson.
He is indirectly mentioned after Professor Proton asks Penny if she has any single grandmothers and she answers that they are both married.