William Douglas (January 17, 1742 – May 28, 1777) was an American military officer who led regiments from Connecticut during the American Revolutionary War. The son of John Douglas (1703-1766) and Olive Spaulding (1709-1752), he was born in Plainfield, Connecticut, Douglas began his military career as a soldier in the French and Indian War, rising to the rank of sergeant. Following the war, he became a shipmaster and worked in the maritime trades until the beginning of the American Revolutionary War, when he raised the 6th Company of the 1st Connecticut Regiment and became its captain.