Eorl was ruler of the Northmen tribe of the Éothéod, who dwelt between the Gladden and the Carrock rivers.
The most renowned fact in his reign was his unexpected arrival in the perilous Battle of the Field of Celebrant to the aid of Gondor.
He may be recognized as the true victor of this battle and was granted lands in Calenardhon by Cirion, Steward of Gondor. He led the migration of his people to these great pastures and there he became the first King of Rohan. He than swore the Oath of Eorl to Cirion.
He was called the Young because at the start of his reign he was in his youth and retained it throughout his reign.
The Rohirrim call themselves the Eorlingas, the Sons of Eorl.
He died in battle in the Wold against the Easterlings.