Lucius Tiberius is a Western Roman procurator or emperor from Arthurian legend in which he is killed in a war against King Arthur. First appearing in Geoffrey of Monmouth's pseudo-historical work Historia Regum Britanniae, Lucius also features in later, particularly English literature such as the Alliterative Morte Arthure and Thomas Malory's Le Morte d'Arthur. The motif of a Roman Emperor defeated by Arthur is found in the Old French literature as well, notably in the Vulgate Cycle.