Lothair Udo I, Margrave of the Nordmark

Lothair Udo I (994-7 November 1057), Margrave of Nordmark and Count of Stade (as Lothair Udo II), son of Siegfried II, Count of Stade, and Adela of Rhienfelden, daughter of Gero, Count of Alsleben. Lothair was the first of the House of Udonids to serve as margrave.

Lothair was in conflict with Adelbert, Bishop of Bremen, over jurisdiction of the county and, in 1053, killed his cousin Ekbert of Elsdorf-Stade, inheriting his land. In 1044, William became Margrave of Nordmark, and, as a Saxon leader, was defeated in 1056 by the Liutizi at the Battle of Pritziawa. Lothair was appointed margrave later that year. This appointment was opposed by Otto, illegitimate son of Bernard, and Lothair was killed by the Otto’s allies on 26 June 1057 at his home at Neindorf on the Selke.

Lothair married Adelheid, Countess of Oeningen, daughter of Count Kuno von Oeningen. Lothair and Adelheid had one son:
 * Lothair Udo II, Margrave of the Nordmark

Lothair also married Ida von Elstorf (d. 1052), daughter of Liudolf, Margrave of Frisia, son of Gisela of Swabia, who was half-brother of Henry III, Holy Roman Emperor. They had two children:
 * Oda of Stade, married Sviatoslav II Yaroslavich, Grand Prince of Kiev. Oda is believed to have arranged the marriage of her nephew Henry III the Long, Count of Stade, to Euproxia of Kiev. The son of Oda and Sviatoslav was Yaroslav Sviatoslavich, Prince of Murom
 * Ekbert, murdered by his half-brother Lothair Udo II in Wickstadt, near Elstorf

Lothair Udo was succeeded by his son and namesake as both margrave and count. After Lothair Udo’s death, his son took vengeance on those who participated in his senseless murder, including his half-brother Ekbert. Otto, the instigator of Lothair Udo's murder, was killed in a battle near Hausneindorf in the summer of 1058.