Even though Supernatural already got one short-lived spinoff, one storyline from season 6 would make an incredibly epic spinoff series – but, unfortunately, it will likely never happen now after the doomed The Winchesters spinoff. Over 15 seasons, Supernatural was no stranger to huge, sprawling storylines with grand consequences. The overarching stakes of most seasons involved a literal world-ending threat, and, upon occasion, Heaven, Hell, and Purgatory ending, too. It's enough that the final season even set up a hypothetical Supernatural season 16.

Of course, that opened the door for many potential spinoff series - it's impossible not to when a show runs as long as Supernatural did. While most of the potential spinoff wishlist involved supporting Supernatural characters that fans grew to love, such as Bobby and Sheriffs Jody and Donna, rarer cases that set up the perfect spinoff involved the plotlines themselves. One of those stories was the biggest missed opportunity of all regarding Supernatural's spinoffs.