No, Supernatural has not done fairies. I kind of wish it would, though, if only because Dean would laugh for about six years while Sam was all pissy at him trying to show him the research about how fairies are SERIOUS BUSINESS. That would be pretty awesome. Especially since Peter J Hammond would not be writing the episode.

If the Doctor is really and truly invested in helping humanity, he would do this. Fewer people would die needlessly if Jack stopped being a dick.