William Augustus Lake (1808–1861) was a U.S. Representative from Mississippi.
Born near Cambridge, Maryland on January 6, 1808, Lake pursued classical studies and was graduated from Jefferson College, Pennsylvania, in 1827. He served as a member of the Maryland house of delegates in 1831, after which he moved to Vicksburg, Mississippi. He studied law, was admitted to the bar in 1834 and started practicing in Vicksburg. He served as member of the State senate in 1848.
Lake was elected as an American Party candidate to the Thirty-fourth Congress (March 4, 1855-March 3, 1857). He was an unsuccessful candidate for reelection in 1856 to the Thirty-fifth Congress. He served in the State house of representatives 1859-1861. He resumed the practice of law. He was a candidate for the Confederate Congress in 1861 and, during the canvass was killed in a duel by his opponent, Colonel Chambers, of Mississippi, October 15, 1861, at Hopefield, Arkansas, opposite Memphis, Tennessee. He was interred in the City Cemetery, Vicksburg, Mississippi.