Henry Knox (July 25, 1750 – October 25, 1806) was an American bookseller from Boston who became the chief artillery officer of the Continental Army and later the nation's first Secretary of War.

Henry Knox was born in Boston to parents of Scots-Irish origin, William Knox and Mary (nee Campbell). His father was a ship's captain who died in 1759 in part due to mental stress arising from financial trouble. Henry left school at the age of 12 and became a clerk in a bookstore to support his mother. He later opened his own bookshop, the London Book Store, in Boston. Largely self-educated, he began to concentrate on military subjects, particularly artillery. Knox joined a local military company at eighteen, was present at the Boston Massacre, and joined the Boston Grenadier Corps in 1772.

Henry married Lucy Flucker (1756–1824), the daughter of Boston Loyalists, on June 16, 1774. In spite of separations due to his military service, they remained a devoted couple for the rest of his life, and carried on an extensive correspondence. Since the couple fled Boston in 1775, she remained essentially homeless throughout the Revolutionary War. Her parents left with the British during their withdrawal from Boston after the Continental Army fortified Dorchester Heights, which ironically hinged upon Knox’s cannons. She never saw them again.