Admiral of the Fleet Sir William Henry May GCB GCVO DL (31 July 1849 – 7 October 1930) was a Royal Navy Officer. As a junior officer he took part an expedition to rescue Commander Albert Markham who had got into difficulty trying to reach the North Pole via Smith Sound, the sea passage between Greenland and Canada's northernmost island, Ellesmere Island.
May went on to higher command and served as Third Sea Lord and Controller of the Navy before becoming Commander-in-Chief, Atlantic Fleet. He held the office of Second Sea Lord and Chief of Naval Personnel and in that capacity threatened to resign if the Liberal Government cut the naval estimates any further. Later he became Commander-in-Chief, Home Fleet, in which capacity he encouraged innovative ways of organising his huge fleet including the deployment of cruising formations, the use of fast squadrons and tactical command at squadron level rather than fleet level, and then became Commander-in-Chief, Plymouth. He served in the First World War purely in an administrative capacity.
May became Director of Naval Ordnance and Torpedoes at the Admiralty in January 1901 and, having been promoted to rear admiral on 28 March 1901, he became Third Naval Lord and Controller of the Navy in April 1901. He was advanced to Knight Commander of the Royal Victorian Order on 30 December 1904. He went on to be Commander-in-Chief, Atlantic Fleet, with his flag in the battleship HMS King Edward VII, in February 1905. Promoted to vice admiral on 29 June 1905, he was appointed a Grand Officer of the French Legion of Honour on 5 September 1905 and a Knight Commander of the Order of the Bath on 29 June 1906.
May became Second Sea Lord and Chief of Naval Personnel in 1907 and in that capacity threatened to resign if the Liberal Government cut the naval estimates any further. In the event he did not have to resign but nevertheless he was cast out of the inner circle of First Sea Lord Sir John Fisher's confidantes.
Promoted to full admiral on 5 November 1908, he became Commander-in-Chief, Home Fleet, with his flag in the battleship HMS Dreadnought, in March 1909. In that capacity he encouraged innovative ways of organising his huge fleet including the deployment of cruising formations, the use of fast squadrons and tactical command at squadron level rather than fleet level. He was advanced to Knight Grand Cross of the Royal Victorian Order on 31 July 1909. He went on to be Commander-in-Chief, Plymouth in April 1911 and was advanced to Knight Grand Cross of the Order of the Bath on 19 June 1911. He was promoted to Admiral of the Fleet on 20 March 1913.
May served in the First World War in an administrative capacity, as a member of the Dardanelles Commission tasked with examining the failure of Gallipoli campaign, as a member of the Reconstruction Committee tasked with considering post-war expenditure reductions and as a member of a fisheries committee. He retired in 1919 and died on 7 October 1930 at his home, Bughtrig House in Coldstream in Berwickshire.