Great-Grandpa Smith, was Stan's paternal grandfather and the father of Jack Smith. In "There Will Be Bad Blood", Stan Smith recounts how he and his half-brother Rusty were given their inheritance. Their grand father had a plot of desert land won by their great-great-grandfather and $20,000. Stan cheated Rusty to take the cash, leaving him with the land which turned out to have vast copper reserves, making Rusty rich.

Great-Grandpa Smith is voiced by Ed Asner.