John Nicholson Inglefield (1748–1828) was an officer in the British Royal Navy.
John Nicholson Inglefield was the son of a ship's carpenter, Isaac Inglefield, and his wife, a sister of the ship designer Thomas Slade, (later Sir Thomas Slade). According to Captain Inglefield himself his paternal family was of Lancashire origin and distantly connected to that of the Englefields.
Under the patronage of his maternal uncle, Thomas Slade, Inglefield joined the navy as a boy of 11 in 1759. In April 1766 he was rated able seaman aboard the Launceston: in May 1768 he was made lieutenant and moved into HMS Romney under the command of Sir Samuel Hood. This connection was to prove the most significant of Inglefield's career. Although Inglefield returned to the Launceston in October, by July 1769 he was back with Hood aboard the Romney and from that time forward his career was closely associated with his friend's. With him Inglefield left the Romney in December 1770, served in HMS Marlborough and HMS Courageux, and in 1778 in HMS Robust with Hood's brother Alexander. Aboard the Robust he was present at the First Battle of Ushant on 27 July.
On 27 December 1773 at Baughurst, Hampshire, Inglefield married Ann Smith, daughter of a gentleman of Greenwich named Robert Smith. They had three daughters and one son, Samuel Hood Inglefield, who also went on to a distinguished naval career and was the father of Sir Edward Augustus Inglefield.
In June 1779 Inglefield was promoted to command of the brig-sloop HMS Lively and in the October of the following year was promoted to post captain and posted to HMS Barfleur of 90 guns, in which his patron, Sir Samuel Hood, hoisted his flag. As captain of the flagship, Inglefield sailed to the West Indies and took part in the skirmish with the French fleet off Martinique in 1781. In August of the same year Hood transferred him to HMS Centaur (74 guns), which Inglefield commanded in three actions against the French, culminating on 12 April 1782 at the Battle of the Saintes.