Gone with the Wind (1936) / Scarlett (1991)
Margaret Mitchell epic Civil War novel evokes a time of civilized plantations, slaves loyal to their masters, and a more genteel Southern era swept away by the wind of Gen. Sherman's march to the sea. Its popularity was enhanced and its fame forever sealed by the 1939 film version, which remains one of the highest-grossing movies of all time.
1991's official sequel, Scarlett was commissioned by the Mitchell estate. It was a commercial hit, though not a very good book. The underwhelming CBS miniseries based on the sequel starred Timothy Dalton as Rhett Butler which, alongside his two James Bond movies, make two franchises that Dalton has sullied.
2007's Rhett Butler's People was yet another unnecessary sequel sanctioned by Mitchell's estate. As God is our witness, we'll never read another one of these again.