Otto I of Nassau

Otto I, Count of Nassau
Spouse(s)	Agnes of Leiningen
Noble family	House of Nassau
Father	Henry II of Nassau
Mother	Matilda of Guelders
Born	c. 1247
Died	1290

Otto I of Nassau (c. 1247–1290), Count of Nassau was the younger son of Count Henry II of Nassau and Matilda of Guelders.

Otto I became the count of Dillenburg, Hadamar, Siegen, Herborn and Beilstein after many years of quarrel with his brother Count Walram II. In the division of 17 December 1255 he received possessions north to the Lahn. And thus began the geographical and political separation of the House of Nassau. He became the founder of the Ottonian line of the house. He stood against the local aristocracy, particularly the counts of Greifenstein and of Dernbach and was for many years banished, since he withheld lands of Teutonic Knights, which his uncle had left to him. Among his opponents were the archbishops of Cologne and Trier, who presented the territorial claims. He lost also the lordships in Emsland and Koblenz.

He married Agnes of Leiningen, a daughter of Count Emich IV of Leiningen and had following children:

He also had an illegitimate son Henry, who was a monk in Arnstein and a priest in Nassau.

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