Artys Arryn

Artys Arryn - also known as The Winged Knight - is an unseen character in Game of Thrones. He is deceased when the events of the series begin. He has only appeared in "The Complete Guide to Westeros: House Arryn" featurette. He was a knight that participated in the Andal invasion of Westeros. He was the founder of House Arryn.

Background
According to legend, Ser Artys flew atop a giant falcon, landing on the topmost mountain of the Vale, and defeated the Griffin King, the last of the First Men Mountain Kings. Afterward, he took the Eyrie and became the first King of Mountain and Vale founding House Arryn. His descendants continued to rule the Vale as Kings until the Targaryen conquest, and then as Lords Paramount of the Vale in the name of the Iron Throne.

In the books
In the A Song of Ice and Fire novels, Ser Artys is the hero of a thousand tales. Robert Arryn, the child lord of the Eyrie, is fond of Ser Artys' stories.