Rear-Admiral William Pierrepont (March 1766 – 7 August 1813) was a Royal Navy officer of the late eighteenth century who is best known for his service in the French Revolutionary Wars as a commander of the frigate HMS Naiad, in which he commanded the British squadron at the action of 16 October 1799 off Vigo, in which one of the largest hauls of prize money ever captured was distributed following the seizure of a Spanish treasure convoy.

It was in Naiad that he achieved a number of successes against French privateers and small warships, including the capture of the en flute frigate Decade in 1798.

In October 1799, while patrolling off Cape Finisterre, Pierrepont spotted and chased two Spanish ships, and although Naiad was unable to catch either one, other patrolling frigates, acting under Pierrepont's direction, were able to bring the Spanish force to battle and defeat it at the action of 16 October 1799.

[1] Ill health forced a temporary retirement in 1800, although he saw shore service in 1803 and returned to sea in 1807 as captain of HMS Zealous.

He married in 1797 and had five children at his stately home of Farley Hill near Godalming in Surrey, where he died aged 46 in August 1813, less than a year after his promotion to rear-admiral.