Edmund Beaufort, 2nd Duke of Somerset, KG (1406 – 22 May 1455), sometimes styled 1st Duke of Somerset, was an English nobleman and an important figure in the Wars of the Roses and in the Hundred Years' War. He also succeeded in the title of 4th Earl of Somerset and was created 1st Earl of Dorset and 1st Marquess of Dorset (previously held by his father and later forfeited), and Count of Mortain. He was known for his deadly rivalry with Richard Plantagenet, 3rd Duke of York.