Duke of Decazes, also called Duke Decazes, is a title of French nobility that was granted in 1820 to Élie Decazes, a French statesman who served as Prime Minister of France from November 19, 1819 to February 20, 1820. He had already been made a French count in 1816. Separately, he was given the hereditary Danish title of Duke of Glücksbierg upon his second marriage in 1818, which title was recognized in France in 1822. In 1826, he founded Houillères et Fonderies de l'Aveyron, a mining and metal-working business in the Aveyron département that marked the beginning of industrialised metallurgy. In 1829, the name of Decazeville was given to the principal centre of the industry.

List of Dukes