Otto III (died 28 September 1057), called the White and known as Otto of Schweinfurt, was the margrave of the Nordgau (1024–1031) and duke of Swabia (1048–1057). He was the son of Henry of Schweinfurt, margrave of the Nordgau, and Gerberga of Henneberg. Otto was one of the most powerful East Franconian princes by inheritance: having extensive land in the Radenzgau and Schweinfurt. In 1014, he first appears as count of Lower Altmühl (or Kelsgau) and, in 1024, he inherits his father's march. In 1034, Otto became count of the Lower Naab. From then on to his appointment to Swabia, he takes part in many imperial expeditions into Bohemia, Hungary, and Poland. He was betrothed to Matilda, daughter of Bolesław I the Brave, but the arrangement fell through.[a]
At Ulm in January 1048, the Emperor Henry III appointed him duke of Swabia after a brief vacancy following the death of Otto II. He was loyal to Henry. He was engaged to marry Matilda, daughter of Boleslaus I of Poland, in 1035, but this was put off in favour of a marriage to Immilla, a daughter of Ulric Manfred, Margrave of Turin, as part of Henry's Italian plans. He was otherwise inactive and died after nine years rule and was buried in Schweinfurt.
By his marriage to Immilla of Turin (died 29 April 1078),[2] he had:
