Knollys, the name of an English family descended from Sir Thomas Knollys (died 1435), Lord Mayor of London. The first distinguished member of the family was Sir Francis Knollys (c. 1514–1596), English statesman, son of Sir Robert Knollys, or Knolles (died 1521), a courtier in the service and favour of Henry VII and Henry VIII. Robert had also a younger son, Sir Henry, who took part in public life during the reign of Elizabeth I and who died in 1583. From the time of Sir Francis, the family were associated with Greys Court at Rotherfield Greys and Caversham Park, then in Oxfordshire, as well as the nearby town of Reading in Berkshire, where the family's private chapel could once be seen in the church of St Laurence.
Francis Knollys, who entered the service of Henry VIII before 1540, became a member of parliament in 1542 and was knighted in 1547 while serving with the English army in Scotland. He became custodian of Wallingford Castle in 1551. A strong and somewhat aggressive supporter of the reformed doctrines, he retired to Germany soon after Mary became queen, returning to England to become a privy councillor, vice-Chamberlain of the royal household and a member of parliament under Queen Elizabeth, whose cousin Catherine Carey (d. 1568), daughter of William Carey and niece of Anne Boleyn, was his wife. After serving as governor of Plymouth, Knollys was sent in 1566 to Ireland, his mission being to obtain for the queen confidential reports about the conduct of the lord-deputy Sir Henry Sidney.