William James Guy Carr (R.D. Commander R.C.N. (R)) (June 2, 1895 - October 2, 1959) was a Canadian naval officer and an author. Though his accounts of wartime naval experiences found a general audience, he is best remembered today as a conspiracy theorist, "the most influential source in creating the American Illuminati demonology", according to the American folklorist Bill Ellis.  Carr was also the author of famous books on the English submarine war as well as a popular lecturer.

In the 1950s, he was the leader of the anti-Communist National Federation of Christian Laymen of Toronto. He was also one of the presidents of the Naval Club of Toronto.

arr was educated in Scotland, and went to sea at the age of fourteen. He served as Navigating Officer of H.M.S. Submarines during World War One (see : Royal Navy Submarine Service) and as Naval Control Officer and Senior Naval Officer in World War Two. In World War II he was Naval Control Officer for the St. Lawrence, then Staff Officer Operations at Shelburne, Nova Scotia, then Senior Naval Officer at Goose Bay, Labrador. As an Officer on the staff of Commodore Reginald W. Brock he organized the 7th Victory Loan for the twenty-two Royal Canadian Naval Training Divisions.

After he retired from the Navy, Carr's writings turned essentially to conspiracy themes from a firmly Christian standpoint. With his Pawns in the Game (1955) and Red Fog over America (1955) he became one of the most famous post-war conspiracy theorists (500 000 copies sold of Pawns in the Game before his death).