William Henry Smyth (21 January 1788 – 8 September 1865) was an English sailor and astronomer. He was the father of Charles Piazzi Smyth, Sir Warington Wilkinson Smyth and General Sir Henry Augustus Smyth. Of his daughters, Henrietta Grace Smyth married Professor Baden Powell and was mother of Robert Baden-Powell, 1st Baron Baden-Powell, while Georgiana Rosetta Smyth married Sir William Henry Flower. He was born in Westminster, London.