Cecily Bonville (c. 30 June 1460 - 12 May 1529) was an English peeress, the suo jure 7th Baroness Harington of Aldingham and suo jure 2nd Baroness Bonville, 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 Wars of the Roses. 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. Lady Jane Grey and Lady Catherine Grey were her great- granddaughters.3145

Upon Lord Bonville's death, his title was passed on suo jure to his great-granddaughter, Cecily Bonville, the seven-and-a-half-months old daughter of his grandson, Lord Harington. Cecily had already succeeded suo jure to the barony of Harington following the deaths at Wakefield in December 1460. In the space of little more than six weeks Cecily Bonville, 2nd Baroness Bonville, 7th Baroness Harington of Aldingham had become the wealthiest heiress in England, having also inherited the vast Bonville and Harington estates. She would go on to marry on 18 July 1474, Thomas Grey, 1st Marquess of Dorset, the eldest son of Elizabeth Woodville, Queen consort of Yorkist king Edward IV, by her first marriage to Sir John Grey of Groby.3134

Cecily's marriage was proposed and arranged by Queen Elizabeth Woodville, who, with assistance from King Edward, persuaded Cecily's stepfather and legal guardian Baron Hastings to agree to the match.3145

Thomas Grey, 7th Baron Ferrers of Groby, 1st Earl of Huntingdon and 1st Marquess of Dorset, KG (c.1455 – 20 September 1501), was an English nobleman, courtier and a man of mediocre abilities pushed into prominence by his mother Elizabeth Woodville's second marriage to the king, Edward IV.3146