Katherine Swynford was a notable figure in the late 14th century, best known as the mistress and later the third wife of John of Gaunt, the Duke of Lancaster. Born around 1350, she was the daughter of a knight and became a lady-in-waiting to Queen Philippa, the wife of King Edward III. Katherine's relationship with John of Gaunt produced four children, who were later legitimized. Her descendants played a significant role in English history, as they included the House of Lancaster and the future Tudor dynasty. Katherine's life and legacy are often associated with themes of love, ambition, and the complexities of noble lineage during the medieval period.