Lotharius

Lotharius is the Latinized form of the Germanic given name Lothar, and it appears in medieval Latin chronicles and charters to refer to several rulers and nobles within the Frankish and Holy Roman realms. The form was especially common from the 9th to the 11th centuries among Carolingian and Ottonian elites, often appearing in Latin-language texts that record their reigns and genealogies.

Notable bearers include Lotharius I (also known as Lothar I) (c. 795–855), who served as King of the East Franks and Holy Roman Emperor from 843 until his death. He was a son of Louis the Pious and played a key role in the early post–Charlemagne imperial structure, attempting to uphold unity among his brothers and their kingdoms after the Verdun settlement. Another prominent figure is Lotharius II (Lothar II) (c. 835–869), who ruled as King of Lotharingia (Lorraine) in the mid-9th century. His reign was centered in the central portion of the former Carolingian realm and was marked by dynastic and political complexities common to the period.

In modern usage, Lotharius appears chiefly in historical writing and in discussions of Carolingian and Ottonian-era politics. The name survives in some languages in the form Lothar, while Lotharius itself is mainly encountered in historical or literary contexts.