Mountain King was a title held by the First Men rulers of the Kingdom of the Mountain and the Vale until the Andal invasion of Westeros. The last of the Mountain Kings was the Griffin King, who was defeated by the "Winged Knight", Ser Artys Arryn. Afterward, House Arryn replaced the line of the Mountain Kings as the rulers of the Vale.
The Mountain Kings were responsible for the construction of the Eyrie, seat of the rulers of the Vale since the Age of Heroes.
