Grandpa Spakenheimer is a character from the Christmas special, Grandma Got Run Over by a Reindeer. He is Grandma's husband, Frank's father, Rita's father-in-law and Jake, Daphne and Cousin Mel's grandfather.
He and his family run a store in Cityville and does not wish to sell it to Austin Bucks, who owns the other properties in town, much to the annoyance of his gold digging granddaughter Mel.
After Grandma mysteriously disappears after being ran over by Santa Claus' sleigh, Grandpa is tricked into selling the store to Mel, with the only way to prevent the sale is if Grandma returned.
Fortunately, Grandma returns and the store is instead franchised throughout the country.