The Griffin King is an unseen character in Game of Thrones. He is deceased when the series begins and has only appeared in "The Complete Guide to Westeros: House Arryn" featurette. He was the last of the Mountain Kings, a First Men dynasty that ruled the Vale since the coming of men to Westeros. He lived at the end of the Age of Heroes and the beginning of the Andal invasion of Westeros.
According to legend, the Griffin King battled Ser Artys Arryn, an Andal known as the Winged Knight, and was defeated. With the death of the Griffin King, the line of the Mountain Kings was extinguished. 
In the books
In the A Song of Ice and Fire books, the Griffin King dueled the Winged Knight atop a mountain known as the Giant's Lance.
- ↑ "The Complete Guide to Westeros: House Arryn" featurette, Season 1 Blu Ray boxset
Garth Greenhand · Florian & Jonquil · The Grey King · The Griffin King · Joramun · Lann the Clever
The Night's King & the Night's Queen· The Rat Cook · The Prince That Was Promised