Eventually, Supernatural did get a spin-off going  a prequel that followed Sam and Dean's parents back in the 1970s. Though it only ran for one season, the series proved to be much more than a prequel.

Titled The Winchesters, the upcoming prequel series follows the story of how Dean and Sam Winchester's parents, John Winchester and Mary Campbell (played by Drake Rodger and Meg Donnelly), first met and fell in love.