Admiral Sir Reginald Aylmer Ranfurly Plunkett-Ernle-Erle-Drax, KCB, DSO, JP, DL (28 August 1880 – 16 October 1967), commonly known as Reginald Plunkett or Reginald Drax, was an Anglo-Irish admiral. The younger son of the 17th Baron of Dunsany, he was Director of the Royal Naval Staff College, President of the Naval Inter-Allied Commission of Control in (Berlin), commander-in-chief of successive Royal Navy bases. His brother Edward, who became the 18th Baron of Dunsany, was best known as the famous playwright and author Lord Dunsany. Edward inherited the paternal estates in Ireland, while Reginald was bequeathed most of his mother's inheritance across portions of the West Indies, Kent, Surrey, Dorset, Wiltshire and Yorkshire. He extended his surname by special Royal licence in 1916, and was noted for the quadruple-name result, Plunkett-Ernle-Erle-Drax.
Drax held a series of senior naval appointments between the wars. From 1919 to 1922, he was Director of the Naval Staff College, Greenwich. He then served as President of the Naval Allied Control Commission in Germany from 1923 to 1924.
As a Rear Admiral, he commanded the 2nd Battle Squadron of the Home Fleet from 1929 to 1930. From 1930 to 1932 he was ashore in the Admiralty as Director of Naval Mobilisation Department that became the Department of Manning.
Promoted to Vice Admiral on 24 September 1932, he held from 1932 to 1934 the much-sought post of Commander of the America and West Indies Squadron.
From 1935 to 1938, he was Commander-in-Chief, Plymouth.