Katherine Stourton, Baroness Grey of Codnor (c. 1455 - 1521) was an English noblewoman. Her life reflects the turbulence of the late fifteenth and early sixteenth centuries: her first husband was attainted for treason, and her third husband holds the record for the longest period of imprisonment in the Tower of London.
She was the daughter of William Stourton, 2nd Baron Stourton and Margaret Chidiock, daughter of Sir John Chidiock. Her father, although not he was not a leading political figure, enjoyed the confidence of Edward IV: in 1469 he sat on the commission of oyer and terminer which condemned Thomas Hungerford of Rowden and Henry Coutenay to death for treason.
About 1475 Katherine married Sir William Berkeley, son of Sir Maurice Berkeley of Beverstone Castle, Gloucestershire; at about the same time her brother John married William's sister, another Katherine. William became a political figure of some importance at the court of Edward IV: he was constable of Southampton and Winchester, organised the entertainment of the King's sister Margaret, Duchess of Burgundy on her visit to England in 1480, and played a considerable role at Edward IV's funeral.
Ross suggests that it was loyalty to Edward's children that led Berkeley, like other members of the royal household, to oppose Richard III. He was one of the leaders of Buckingham's revolt in October 1483. After the failure of the revolt, Berkeley, unlike many of the rebels, did not immediately flee the country, having some hope of a pardon. The Parliament of 1484 attainted him as a traitor, but in March he was pardoned, Katherine's brother John standing surety for his good behaviour. Soon after he abandoned the Yorkist cause for good and joined the future Henry VII in Brittany. After Henry's victory at the Battle of Bosworth the Berkeley lands were restored, and several court offices promised to William; but he was probably already a sick man (he made a codicil to his will in September 1485), and seems to have died early in 1486. He and Katherine had no children.