Guy Johnson (c. 1740 – 5 March 1788) was a British Indian Department officer, judge and politician. He served on the side of the British during the American Revolutionary War, having migrated to the Province of New York as a young man and worked with his uncle, Sir William Johnson, 1st Baronet who served as the Superintendent of Indian Affairs of the northern colonies.
Guy was appointed as William's successor in 1774. The following year, Johnson relocated with Loyalist supporters to Canada as tensions rose in New York during the American Revolution. He directed joint British-Mohawk military actions in the Mohawk Valley. Accused of falsifying reports, he went to London to defend himself after the war, and died there in 1788.