The Landgrave of Hesse was a title used by the rulers of the historical region of Hesse in Germany. This title originated in the 13th century and was held by various noble families, most notably the House of Hesse. The Landgraves played a significant role in the political landscape of the Holy Roman Empire and were influential in the Protestant Reformation. The territory of Hesse was divided into several regions, including Hesse-Kassel and Hesse-Darmstadt, each ruled by different branches of the family. The Landgraves were known for their contributions to culture, economy, and military affairs, shaping the development of the region throughout the centuries.