Duke Leopold was a title held by various noble figures in European history, particularly in the regions of Austria and Belgium. The most notable Duke Leopold was Leopold I of Belgium, who became the first King of the Belgians in 1831. He played a significant role in establishing Belgium as an independent nation after its separation from the United Kingdom of the Netherlands. Another prominent figure was Leopold II, who ruled as King of the Belgians from 1865 to 1909. He is often remembered for his controversial reign, particularly regarding his exploitation of the Congo Free State, which he personally owned. His actions in the Congo led to significant humanitarian crises and have left a lasting impact on the region's history.