Menumorut, or Menumorout (; ; ), was the ruler of the lands between the rivers Mureș, Someș and Tisza at the time of the Hungarian conquest of the Carpathian Basin around 900, according to the Gesta Hungarorum, a Hungarian chronicle written after 1150 by an unidentified author, referred to as Anonymus. Historians debate whether Menumorut was an actual ruler or a fictional character created by the author, since the Gesta tells of multiple figures, including Menumorut, who are not identified in any other primary sources, and does not name any of the enemies of the invading Hungarians written of in other contemporary accounts of the invasion. According to Anonymus, Menumorut's duchy was populated primarily with Khazars and Székelys, and he acknowledged the suzerainty of the (unnamed) ruling Byzantine Emperor at the time.
In Romanian historiography, the consensus describes Menumorut as one of the three Romanian rulers who attempted to resist the Magyar conquest of the intra-Carpathian regions of present-day Romania. According to the Gesta, the Magyars eventually besieged and seized Menumorut's fortress at Biharia, and forced him to give his daughter in marriage to Zoltán, the son of Árpád, the Grand Prince of the Hungarians. The chronicle states that Menumorut died around 906 and was succeeded by his son-in-law.