Landgrave Frederick I of Hesse-Cassel (1747-1837) was a German nobleman who ruled the Landgraviate of Hesse-Cassel. He was a member of the House of Hesse and played a significant role in the political landscape of Germany during his time. Frederick I is known for his efforts to modernize his territory and improve its economy. Frederick I was also notable for his military alliances, particularly during the Napoleonic Wars. He supported the Holy Roman Empire and later aligned with the Allies against Napoleon Bonaparte. His reign contributed to the development of Hesse-Cassel as a significant state in the region.