Brego was the second King of Rohan.
Brego became King at the death of his father Eorl the Young in 2545 (Third Age). During his rule the migration of the Éothéod to Calenardhon continued, and Brego defended the borders of Rohan against their enemies (the Dunlendings and Easterlings).
Brego built the Golden Hall of Meduseld, and made Edoras the capital of Rohan.
His eldest son Baldor in his pride went into the Paths of the Dead never to be found again, and Brego died of grief soon after. He was followed by his second son, Aldor.
In Peter Jackson's the movie version of The Two Towers, Aragorn rides a horse named Brego, apparently named after this king.