Supernatural should look to one classic villain for an arch-nemesis if it springs back to life. Supernatural season 15 ended with Dean Winchester (Jensen Ackles) dying fighting vampires and Sam Winchester (Jared Padalecki) surviving him, growing old until his final end, and reunion with Dean and other old pals in the afterlife. This genuinely wonderful ending hasn’t stopped legions of fans from campaigning for more Supernatural, which always seemed to have more to offer after it looked like it had died a final death. One villain may be the key to a revival, offering Eric Kripke a route forward.