Grandpa Shumway (1149-1801) was a Melmacian inventor.
His father was the inventor of extra wide dental floss. (ATAS: "Thank Gordon for Little Girls") His grandfather was Sherman Shumway, Supreme Commander of the Orbit Guard. (ATAS: "Two for the Brig")
He and his wife, Grandma Shumway, were the parents of Bob Shumway, and the paternal grandparents of Gordon, Curtis, and Augie Shumway.
Bob recalled that Grandpa had impressed upon him the value of deferring to the judgement of experts. (ATAS: "Pride of the Shumways")
Grandpa was noted for his invention of the electric cat opener. (ATAS: "Thank Gordon for Little Girls")
Background[]
In "He Ain't Seafood, He's My Brother," Bob visited "Grandma's house." This may indicate that Grandpa had already passed away, the two had divorced, or perhaps that they were never married.