Edmund Beaufort
Stafford married Lady Margaret Beaufort, daughter of Edmund Beaufort, 2nd Duke of Somerset and Lady Eleanor Beauchamp. Lady Margaret was the sister of Henry Beaufort, 3rd Duke of Somerset (executed 15 May 1464 after the Battle of Hexham) and Edmund Beaufort, 4th Duke of Somerset (executed 6 May 1471 after the Battle of Tewkesbury). Her maternal grandparents were Richard de Beauchamp, 13th Earl of Warwick and his first wife Elizabeth Berkeley. By her father, she was a niece of Joan Beaufort, Queen of Scots and a cousin to Lady Margaret Beaufort (mother of King Henry VII). By her mother, Lady Margaret was a niece of Anne de Beauchamp, 16th Countess of Warwick and as such, a cousin to Isabel, Duchess of Clarence and queen consort Anne Neville.