Dennis Hart Mahan [m?'hæn] (April 2, 1802 – September 16, 1871) was a noted American military theorist, civil engineer and professor at the United States Military Academy at West Point from 1824-1871.
He was the father of American naval historian and theorist Rear Admiral Alfred Thayer Mahan.
Of his other four children, his son Frederick August Mahan also graduated from West Point in 1867.