One of the warriors of the Rohirrim who fought among the armies of Théoden at the Battle of the Pelennor Fields. His name is listed among the dead in the Song of the Mounds of Mundburg, suggesting that he was a lord in Rohan, or at least an officer of some kind, though no further details of his life are known.

'Horn' means the same in Old English as in modern English, but the name is perhaps an echo of the romantic hero King Horn, whose story dates back to at least the twelfth century. Tolkien was certainly familiar with that tale - it holds the ultimate origin of the name Westernesse - so Horn's name among the roll of the dead of the Battle of the Pelennor may well be a nod to that old English tradition.