1495 – 19 March 1553) was an English nobleman, politician, courtier, and Master of Burghley (Burleigh) in the parish of Stamford Baron, Northamptonshire.

His father Sir David Cecil, of Welsh ancestry, rose in favour under King Henry VIII of England, becoming High Sheriff of Northamptonshire in 1532 and 1533, and died in 1541.

In 1517 he was a royal page; in 1520 he was present at the Field of the Cloth of Gold; he rose to be Groom of the Robes and constable of Warwick Castle.

Academically a success, William ran foul of his father, when his heart was lost to Mary Cheke, daughter of a local widow, with only a fortune of 40 pounds to recommend her.

Thomas, the future Earl of Exeter and only fruit of this union was born at Cambridge on 5 May 1542, therefore presumably at his grandmother's house.