King of the Andals, the Rhoynar, and the First Men

The King of the Andals, the Rhoynar, and the First Men was the first of three titles taken by the monarch of the Seven Kingdoms of Westeros. The one who donned this title claimed rulership of all seven kingdoms, including Dorne despite the southern kingdom's frequent resistance to the dominion of the Seven Kingdoms.

History
The title was established during Aegon's Conquest and persisted after, claimed by whomever sat the Iron Throne of Westeros.