The First King as depicted in Game of Thrones: Histories & Lore.
Fire & Blood (mentioned)|
The World of Ice & Fire (mentioned)
A Dance with Dragons (mentioned)
It was under the First King's leadership that the First Men traveled across the Arm of Dorne from Essos to Westeros. In contrast to the northern legend of the First King, some legends from the Reach claim that Garth Greenhand was the High King of the First Men who led his people to Westeros.
According to folklore the Great Barrow in Barrowton contains the grave of the First King or a King of the Giants. Passages of the Dead by Maester Kennet mentions a curse placed on the Great Barrow which prevents any living man from rivaling the First King. The monarch was succeeded by the Barrow Kings.