Richard de Clare, remembered to history as Strongbow, also owned Goodrich and Usk Castles and was a major player in the conquest of Ireland.
He now stars as the "baddie" in Ruadh Butler's new novel, Swordland.
Mr Butler said: "Monmouthshire in this period was a land of Norman castles and Welsh bandits, and one man of Gwent, Richard de Clare, who was better known to history as Strongbow, would go on to become synonymous with the Cambro-Norman conquest of Ireland."
Swordland explores the story of the Welsh Marches and the people from so many backgrounds vying to control it.
It is a tale as bloody as any chapter from Game of Thrones but unlike Game of Thrones, this tale isn't fictional; the events in the book were real and carried out by our ancestors.