Mary Osborne, Duchess Of Leeds

Mary Osborne, Duchess of Leeds (23 November 1723 – 3 August 1764), was born Lady Mary Godolphin. She was the daughter of Henrietta Godolphin, née Churchill, 2nd Duchess of Marlborough, and Francis Godolphin, 2nd Earl of Godolphin. Her maternal grandparents included John Churchill, 1st Duke of Marlborough, and Sarah, Duchess of Marlborough, placing her within a prominent family connected to key figures in British political and military history during the reign of Queen Anne of Great Britain. Her paternal grandparents included Sidney Godolphin, 1st Earl of Godolphin.

There are claims that Lady Mary was the illegitimate child of William Congreve, a noted playwright, with whom her mother Henrietta Churchill was reported to have had a long-term relationship. However, she was recognized by her father, Francis Godolphin, as his own daughter and was brought up alongside her full siblings. Despite official recognition, rumors about her paternity persisted, leading to her maternal grandmother, the Duchess of Marlborough, not acknowledging her publicly until 1740. In that year, the two reconciled, and her family circumstances became clearer.

In 1740, Sarah, Dowager Duchess of Marlborough, arranged Lady Mary's marriage to Thomas Osborne, 4th Duke of Leeds. Their marriage took place on 26 June 1740. The marriage produced one surviving child, Francis Godolphin Osborne, who was born on 29 January 1751. His titles included Marquess of Carmarthen, and he later became the 5th Duke of Leeds, as well as serving as Secretary of State for Foreign Affairs.

Mary, Duchess of Leeds, died in 1764 at the age of 40.