Sir Percy James Grigg, KCB, KCSI, PC (16 December 1890 – 5 May 1964), often referred to as P J Grigg and later better known as Sir James Grigg, was a British civil servant who was unexpectedly moved, at the behest of then-Prime Minister Winston Churchill, from being the Permanent Under-Secretary of State at the War Office to become Secretary of State for War, the political head of the same department during the Second World War.