Vice-Admiral Peter John Douglas (30 June 1787 – 17 December 1858) was an officer of the Royal Navy who served during the French Revolutionary and Napoleonic Wars.

[3] He entered the Navy on 17 January 1797 and during the next six years served on a variety of ships, including the 90-gun HMS Sandwich, commanded by his father.

On 25 October 1805 Douglas, whilst serving on the frigate HMS Franchise, commanded one of the ship's boats at the capture, on the north side of Jamaica, of the privateer General Ferrand, and, on the night of 6 January 1806, he had charge of the barge, and elicited the highest approbation for his promptitude and gallantry at the taking, in the Bay of Campeche, of the Spanish corvette Raposa, at which he was wounded.

Prior to leaving the Franchise, he further served in the boats at the capture of the Spanish schooner Carmen, and on board that ship he succeeded in making two prizes, and in driving an armed vessel on shore.

On 30 March 1838, he was appointed Commodore on the Division of North America and West Indies Station and superintended the naval establishment Jamaica Dockyard and in the November following he was sent in command of a large squadron to the Gulf of Mexico, to mediate between the French and Mexican governments.