Movies that were supposed to launch franchises (but didn’t): Supergirl
Alexander and Ilya Salkind paid a pretty penny for the rights to Superman. After three movies, star Christopher Reeve was ready to call it quits as the Man of Steel, but the Salkinds thought there might still be some money to by wrung out of their intellectual property. So they decided to spin off Supergirl into her own movie franchise. Unfortunately, it didn’t take flight.