The Duke of Sudermania is a title in the Swedish nobility, historically associated with the province of Södermanland. The title was created in the 17th century and has been held by various members of the Swedish royal family. It is one of the many ducal titles in Sweden, reflecting the country's rich history of nobility and governance. The title is often linked to the Crown Prince of Sweden, who traditionally holds it. The Duke of Sudermania plays a ceremonial role and is involved in various cultural and charitable activities within the region, promoting local heritage and community engagement.