John Thurloe[1] (June 1616 – 21 February 1668) was an English politician who served as secretary to the council of state in Protectorate England and spymaster for Oliver Cromwell and held the position of Postmaster General between 1655 and 1660.

He was first in the service of Oliver St John, solicitor–general to King Charles I and Lord Chief Justice of the Common Pleas.

In March 1651, Thurloe accompanied Oliver St John as his secretary on his embassy to the United Provinces to propose a union between the Commonwealth and the Dutch.

Thurloe's service broke the Sealed Knot, a secret society of Royalists and uncovered various other plots against the Protectorate.

(Ironically, Thurloe's own department was also infiltrated: in 1659 Morland became a Royalist agent and alleged that Thurloe, Richard Cromwell and Sir Richard Willis – a Sealed Knot member turned Cromwell agent – were plotting to kill the future King Charles II.)

About forty years after his death, a false ceiling was found in his rooms at Lincolns Inn; the space was full of letters seized during his occupation of the office of Postmaster-General.

He retired from public life but served as a behind-the-scenes authority on foreign affairs and wrote informative papers for Edward Hyde, but he did not become part of any new government.

[13] Apart from building his mansion in Wisbech, in 1658 he gave £50 to purchase books for the Public library[14] and contributed eighty-one volumes and £50 for making a road 'from the corn market to the little sluice' and £150, the interest to be applied towards putting out poor children apprentice.