The War of the Katzenelnbogen Succession or the Katzenelnbogen Succession Struggle (1500–1557) was a war of succession about the County of Katzenelnbogen after the death of William II "the Younger", Landgrave of Hesse. In the end, Philip I, Landgrave of Hesse won the conflict. William I "the Rich", Count of Nassau-Siegen, known for being the father of William the Silent en Johann VI, Count of Nassau-Dillenburg, lost the war and got himself into deep financial troubles.

The County of Katzenelnbogen was an immediate state of the Holy Roman Empire. It existed between 1095 and 1479, when it was inherited by the Landgraves of Hesse.