User blog comment:BalrogLune/Aliens in Supernatural/@comment-5619706-20121014155937

Aliens would make this show Sci-Fi, which it is not. It's fantasy. Aliens, no matter how you put it, would belong in the Sci-Fi. If you are going to work on them as beings from another dimension (same as faeries), fine. But once you give them spaceships and guns and advanced technology, no matter how mystic it appears, it destroys the show.

I know some supernatural events could be seen as results of extremely advanced technology, but that thin line is what differentiates Fantasy from Sci-Fi.