Admiral of the Fleet Sir John Donald Kelly GCB, GCVO (13 July 1871 – 4 November 1936) was a Royal Navy officer. He served in the First World War as commanding officer of the cruiser HMS Dublin which came close to intercepting the German battlecruiser SMS Goeben. After the War he took charge of a naval force dispatched to strengthen the Mediterranean Fleet during the Chanak Crisis. After serving as Fourth Sea Lord and then commander of the 1st Battle Squadron, Kelly, known for his skill in personnel matters, was asked to take command of the Atlantic Fleet in the aftermath of the Invergordon Mutiny. He rapidly restored discipline and issued a report which was quite critical of the Admiralty Board's handling of the pay cuts issue in the first place. He went on to be Commander-in-Chief, Portsmouth.
Born the second son of Lieutenant-Colonel Henry Holdworth Kelly of the Royal Marine Artillery and Elizabeth Kelly (née Collum), Kelly joined the training ship HMS Britannia as a cadet on 15 January 1884. Promoted to midshipman on 15 November 1886, he joined the corvette HMS Calliope in January 1887. He transferred to the armoured frigate HMS Agincourt in the Channel Squadron in August 1888, to the battleship HMS Anson in the Channel Squadron in May 1889 and then to the corvette HMS Volage in the Training Squadron in September 1889. Promoted to sub-lieutenant on 14 February 1891 and to lieutenant on 31 December 1893, he joined the cruiser HMS Katoomba on the Australia Station in February 1894. He transferred to the cruiser HMS Royal Arthur, flagship of the Australia Station, in November 1897 and, after qualifying in gunnery at the gunnery school HMS Excellent in 1901, he became gunnery officer in HMS Forte on the Cape of Good Hope and West Coast of Africa Station and saw action in her during the Second Boer War.
Promoted to commander on 30 June 1904, Kelly became Executive Officer in the armoured cruiser HMS Sutlej on the China Station in November 1904, Executive Officer in the cruiser HMS Hawke in the Reserve Fleet in 1906 and Executive Officer in the battleship HMS Cornwallis in the Atlantic Fleet in January 1907. He went on to be a member of the teaching staff at the Royal Naval College, Dartmouth in July 1908 and, having been promoted to captain on 22 June 1911, he became a member of the teaching staff at the Royal Naval War College in October 1912 and Captain of the School of Physical Training at Portsmouth in January 1913. He then became commanding officer of the light cruiser HMS Hermione in the Home Fleet in April 1914 and commanding officer of the cruiser HMS Dublin in the Mediterranean Fleet in July 1914.