Otto I was the Duke of Swabia from 973 and Duke of Bavaria from 976. He was a member of the Ottonian dynasty, the only son of Duke Liudolf of Swabia and his wife Ida, and thus a grandson of the Emperor Otto I and his Anglo-Saxon wife Eadgyth. His sister Mathilde was the abbess of Essen Abbey.

The Dukes of Swabia were the rulers of the Duchy of Swabia during the Middle Ages. Swabia was one of the five stem duchies of the medieval German kingdom, and its dukes were thus among the most powerful magnates of Germany. The most notable family to rule Swabia was the Hohenstaufen family, who held it, with a brief interruption, from 1079 until 1268. For much of that period, the Hohenstaufen were also Holy Roman Emperors. With the death of Conradin, the last Duke of Hohenstaufen, the duchy itself disintegrated although King Rudolf I attempted to revive it for his Habsburg family in the late 13th century.