Knox County is a county located in the U.S. state of Texas. As of the 2020 census, its population was 3,353. Its county seat is Benjamin. The county was created in 1858 and later organized in 1886. It is named for Henry Knox, an American Revolutionary War general.

Henry Knox, a Founding Father of the United States, was a Boston bookseller who became a senior general of the Continental Army during the Revolutionary War, serving as chief of artillery in most of Washington's campaigns. Following the American Revolution, he oversaw the War Department under the Articles of Confederation from 1785 to 1789. Washington, at the start of his first administration, appointed Knox the nation's first Secretary of War, a position he held from 1789 to 1794. He is well known today as the namesake of Fort Knox in Kentucky, the repository of a large portion of the nation's gold reserves.