Éomund was the Chief Marshal of the Mark of Rohan under Théoden King in the years leading up to the War of the Ring. He was also the father of Éomer and Éowyn, and the husband of Théodwyn, sister of Théoden. Éomund was a distant descendant of Éofor, one of the sons of Brego King son of Eorl.
A valiant captain, Éomund was often away defending the East-Mark against the growing threat of thieving Orcs coming west from Mordor. It was said that he was also reckless, often riding against the enemy with few men. In the year TA 3002, he was slain pursuing a band of Orcs towards the Emyn Muil. Éomer was 11, Éowyn 7; and soon Theodwyn became ill and died. Thereafter the children of Éomund were fostered by the King; and they were beloved by Théoden. Éomer went on to become King of the Mark, and wedded Lothíriel, Princess of Dol Amroth, and Éowyn wedded Faramir, Steward of Gondor. Their children were Elfwine the Fair, 19th King of Rohan, and Elboron, Prince of Ithilien, respectively. Thus was the House of Éomund renowned at the dawn of the Fourth Age.