Eric Kripke's Supernatural had an impressive run at a whopping 15 seasons, but there were still some storylines the creator had in his back pocket but never used. The show started in 2005, and by the time it wrapped up in 2020, it gained a serious cult following. Supernatural evolved over the years from a mainly horror- and mystery-driven series into one that could also juggle zany comedy and science fiction elements.
Supernatural tells the story of two brothers, Sam and Dean Winchester (played by Jared Padalecki and Jensen Ackles, respectively), who drive Supernatural's signature vehicle, their dad's '67 Chevy Impala, across the country hunting nearly every kind of ghost, demon, witch, or creature imaginable and traveling to a host of haunted locations. Most of these entities and places are based on real folklore or urban legends from the United States and elsewhere, such as the H.H. Holmes Murder Castle in Chicago, Roanoke, or the Hookman legend. Several of the show's seasons also deal with the Christian lore of angels, demons, and the Biblical apocalypse.
Around the time that Supernatural season 13 aired, Kripke took to Twitter to dump a huge list of ideas he had when starting the series. Interestingly enough, Supernatural's original plan didn't feature the Winchester brothers. Kripke's two-page list features many concepts that fans will recognize, but there's a surprising number of ideas on the list that never made it to the screen or, at least, never got their own dedicated episode.
Some of the creatures on Kripke's list get passing mentions in the show, either turning up in John Winchester's journal or in Dean and Sam's conversations with other hunters. These include Spring-heeled Jack (a Victorian-era urban legend from the U.K.), chupacabras, Mothman, and Jersey Devils. For example, the brothers think they are hunting a Jersey Devil in season 7, episode 9 before realizing it's really a Leviathan, one of Supernatural's more criticized ideas. Other cryptids never made the cut at all, like sea serpents, Thunderbirds, the Dover Demon, and the Alpine Tatzelwurm, a lizard-like creature with the face of a cat. Perhaps the most disturbing of Kripke's unused creature ideas are the "Faceless Gray Man who appears before hurricanes in South Carolina" or "Old Hag Syndome [sic]," which is a reference to sleep paralysis demons.
Supernatural also deals with real people and locations from history, and Kripke's unused ideas include several ghoulish figures and places. Antoine LeBlanc was a 19th-century murderer from New Jersey whose skin was sold as souvenirs to those who witnessed his hanging, and Count Von Cosel, a.k.a. Carl Tanzer, was a radiology technician in Florida who stole and preserved the body of a patient he was in love with. Kripke also toyed with featuring famed Voodoo practitioner Marie Laveau and the Mad Gasser of Mattoon. Supernatural could have seen Dean and Sam Winchester travel to the Hull House in Chicago where a supposed devil baby was born, the Bell Witch Cave in Tennessee, or several haunted Chicago cemeteries. Perhaps the biggest missed opportunity on Kripke's list is the Winchester Mystery House, built by Sarah Winchester supposedly to hide from the ghosts of those killed by her family's rifles. Since Sam and Dean are part of the Winchester line as well, it would have made sense for the brothers to visit in one of Supernatural's hundreds of episodes.
While it's for the best that a few of these unused ideas never made it into Supernatural—it would be impossible to play on the 1932 film Freaks or the Hickory Hill slave house in Chicago in good taste, no matter Kripke's intentions—most of them would have been fun to see come to life. Though many fans hated the Supernatural finale, the fan base generally seems to love the series' endless capacity for wacky and terrifying content during its 15 seasons. Even without all of creator Eric Kripke's unused ideas gracing the annals of Supernatural's history, the show will likely remain a cult classic for a long time.