Cecily Bonville, 7th Baroness Harington and 2nd Baroness Bonville (c. 30 June 1460 – 12 May 1529) was an English peeress, who was also Marchioness of Dorset by her first marriage to Thomas Grey, 1st Marquess of Dorset, and Countess of Wiltshire by her second marriage to Henry Stafford, 1st Earl of Wiltshire.
The Bonvilles were loyal supporters of the House of York during the series of dynastic civil wars that were fought for the English throne, known as the Wars of the Roses (1455 – 1485). When she was less than a year old, Cecily became the wealthiest heiress in England after her male relatives were slain in battle, fighting against the House of Lancaster.
Cecily's life after the death of her first husband in 1501, was marked by an acrimonious dispute with her son and heir, Thomas Grey, 2nd Marquess of Dorset. This was over Cecily's right to remain sole executor of her late husband's estate and to control her own inheritance, both of which Thomas challenged following her second marriage to Henry Stafford; a man many years her junior. Their quarrel required the intervention of King Henry VII and the royal council.
Lady Jane Grey, Lady Catherine Grey and Lady Mary Grey were her great-granddaughters. All three were in the Line of Succession to the English throne. Jane, the eldest, reigned as queen for nine days in July 1553.
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