Jon Karstark

Jon Karstark is an unseen character in Game of Thrones. He is not expected to appear in the series, being long dead by the time it starts. He is one of the earliest recorded members of House Karstark, and an ancient ancestor of Lord Rickard Karstark.

Background
Jon Karstark was the first born son of Commard Karstark and his wife Regan.

Season 1
He has an entry in The Lineages and Histories of the Great Houses of the Seven Kingdoms.

In the books
Jon Karstark is referenced only in the TV adaptation of A Song of Ice and Fire and has no corresponding counterpart in the books.