The Duke of Lancaster is a title in the British peerage, traditionally held by the reigning monarch. This title is associated with the historic county of Lancashire in England. The Duke of Lancaster has various ceremonial and administrative roles, particularly in relation to the Duchy of Lancaster, a portfolio of land, property, and assets that generates income for the monarch. The title has a rich history, dating back to the 13th century, and has been held by notable figures, including King Henry IV. The current Duke of Lancaster is King Charles III, who assumed the title upon his accession to the throne in September 2022.