Luthor Tyrell was the eldest son of Theodore Tyrell, Lord Paramount of the Reach. He was wed to Lady Rohanne of House Florent as part of a series of marriage pacts arranged by his father to unify the reach following the devastating War of the Split Stag. The couple sired three children; Leonette, Baelor, and Lyonel Tyrell. He has an elder sister and younger brother, Merianne and Hoster Tyrell.
Luthor ruled as Lord Paramount of the Reach from 452-479 AC. Unlike his diplomatic father, Luthor did not have the same forgiving mentality towards the lords who fought against House Tyrell in the civil war of his youth. The most notable of these lords was Old Garth Hightower. One of Luthor's first acts as Lord Paramount was to break the betrothal between his sister and Hightower's heir in favor of one between Merianne and King Orys II Baratheon instead. The marriage saw a renewed bond formed between the Reach and the Iron Throne and led to much prosperity for both. The relations between House Hightower and Tyrell however only worsened, and old wounds were deepened because of the slight.