William Henry Dawnay, 6th Viscount Downe (20 August 1772 – 23 May 1846), styled The Honourable William Henry Dawnay until 1832, was an English clergyman and Irish peer. William was the second son of John Dawnay, 4th Viscount Downe. Educated at Eton, he became friends there with the son of Giles Earle (d. 1811). He matriculated at Christ Church, Oxford in 1790, receiving his BA in 1795 and his MA in 1796. On 6 June 1811, William married Lydia Heathcote daughter of John Heathcote of Connington Castle, by whom he had three children: