Ernest I, Duke of Brunswick-Lüneburg (1497-1546) was a German nobleman and a member of the House of Welf. He became Duke of Brunswick-Lüneburg in 1520 and played a significant role in the political landscape of northern Germany during the Reformation. His reign was marked by efforts to strengthen his duchy and maintain its independence. Ernest I was known for his support of the Lutheran Reformation, which influenced the religious direction of his territory. He worked to establish Protestantism in his lands while navigating the complex relationships with other German princes and the Holy Roman Empire. His leadership helped shape the future of the region.