Duchess of Cornwall is a title held by the wife of the heir apparent to the British throne. The Duchess of Corwall generally holds the title of Princess of Wales with the exception of Prince Charles, the then-duke of Corwall, wife, Camilla, Duchess of Corwall. The current title-holder is the duke of Cornwall's wife, Catherine, since September 8, when King Charles III succedeed his mother and he became Prince of Wales.
Duchesses of Cornwall
Until her husband's accession to the throne, Camilla, the second wife of the then-prince of Wales, used the title 'Duchess of Cornwall' rather than 'Princess of Wales', as the latter was still popularly associated with Charles's first wife, Diana, who died in 1997.
Literary references
Arthurian legend depicts Cornwall with its own ducal family. Notably, King Arthur's mother, Igraine, would have been Duchess of Cornwall from her first marriage to Duke Gorlois; in some stories, the title is then passed on to their daughter, Morgan le Fay. Shakespeare's King Lear includes the character "Regan, Duchess of Cornwall", Lear's second daughter.