The king asleep in mountain (D 1960.2 in Stith Thompson's motif index system)[1] is a prominent folklore trope found in many folktales and legends.
"[citation needed] The herdsman in this story was then supernaturally harmed by the experience: he ages rapidly, he emerges with his hair turned white, and often he dies after repeating the tale.
The story goes on to say that the king sleeps in the mountain, awaiting a summons to arise with his knights and defend the nation in a time of deadly peril.
Major examples are King Arthur of Britain, Charlemagne of the Franks, and Holy Roman Emperor Frederick Barbarossa, as well as [8][9] Ogier the Dane and William Tell.
Sometimes this type of story or archetype is also attached to not-so-heroic figures, who are either simple anti-heroes or fully villains, whose return would mean the end of the world, or whose sleep represents something positive.