Lower Lorraine (Lothier) was a duchy, part of the former Carolingian Kingdom of Lotharingia, that was created in 959 by Bruno I, Archbishop of Cologne, who divided the territory that had been the northern part of Lotharingia, which he had been assigned by his brother Otto I, in two duchies.

The southern part of this new division, the duchy of Upper Lorraine had a longer career, eventually becoming Lorraine.

The northern part of the territories, Lower Lorraine, was quickly further divided.

The ducal title lapsed in about 1180 and other assignments of title occurred.

See list of holders of the title at Duke of Lower Lorraine.