The Great Doc is the great-great-uncle of Doc on Fraggle Rock. The Great Doc was a vaudeville magician, who toured the country, playing such theaters as the Victoria and the Schubert. His assistant was his dog, a top-hatted canine (closely resembling Sprocket) named the Great Pooch.
Doc finds his great-great-uncle's trunk in the attic in the second season episode "The Wizard of Fraggle Rock." While practicing the Great Doc's rope trick, however, Doc and Sprocket inadvertently tie themselves up, unable to undo the bonds.