John Armstrong (April 20, 1755 – February 4, 1816) was an American soldier and judge.
His service record is sometimes confused with the more famous John Armstrong, Jr., a Pennsylvania officer who became U.S. Secretary of War.
Armstrong rejoined the United States Army in 1784 and served during the Northwest Indian War.
Later that year he led a detachment of regular soldiers that accompanied Kentucky militia under Colonel John Hardin in an expedition to attack a Native American village on the Eel River.
The Americans were ambushed in the battle; the militia fled and Armstrong barely escaped with his life.