HMS Mermaid was a 32-gun Active-class fifth-rate frigate of the Royal Navy, launched in 1784 and broken up in 1815. During the French Revolutionary Wars she served in the West Indies, the Channel, and the Mediterranean. During the Napoleonic Wars she first served in the Americas, but from early 1811 on, she was armed en flute and served as a troopship until she was broken up.

Mermaid was one of the eight-ship Active class, designed by Edward Hunt. She was initially ordered from the shipwright George White, of Woolwich Dockyard Shipwright on 27 August 1778, and laid down in September 1778, but the order moved to John Jenner in April 1779. On 21 March 1782 the order was canceled and moved instead to Thomas Pollard, at Sheerness Dockyard, and the frigate was again laid down, on 29 July 1782. She was launched on 29 November 1782, and commissioned for the ordinary on 30 December 1784. She was commissioned again between June and August 1790 for sea duty. She had cost £12,854 to build, with another £2,539 paid for her fitting out in 1790. The Woolwich work had cost £1,807.

Mermaid was commissioned under Captain Cuthbert Collingwood in June 1790 during the Nootka Crisis. She sailed to the West Indies, but returned in April 1791 and was then paid off.

She was again fitted out, this time at Portsmouth for £3,446, between February and May 1793, commissioning in March that year under Captain John Trigge. She was assigned to the Mediterranean, departing Britain on 22 May 1793. On 27 May she and Tartar captured the 20-gun privateer Général Washington, and on 30 May 1793 Mermaid and Castor captured the 16-gun privateer Angélique. Mermaid also captured a 14-gun privateer in June that year. Mermaid then joined Admiral Samuel Hood's fleet at Toulon.

She came under the command of Captain Henry Warre in June 1794, and then sailed to the Leeward Islands on 5 May 1794. There on 10 October 1795 Mermaid captured the 10-gun Brutus off Grenada. However, the brig's crew of 50 men, together with some 120 troops, were able to get ashore before Mermaid could capture them. Brutus had been in the company of a ship that temporarily escaped. On 14 October Mermaid was able to find and capture the ship after a fight that cost Mermaid one man killed and three men wounded. The French ship was the French corvette Republicaine; she was armed with eighteen guns and had some 250–260 men aboard at the start of the action, one of whom was a French general on his way to take command of Grenada. In the action, the French lost 20 men killed and some wounded. Zebra shared by agreement. The Royal Navy took Republicaine into service as HMS Republican.

On 30 October 1795 Robert Waller Otway received promotion to post-captain; he took command of Mermaid the next month at Grenada. In February 1796 Mermaid briefly came under the command of Captain Charles Davers, but by April Otway had returned.

At the time Grenada and several of the other islands were in a state of insurrection, with the slaves joining the French inhabitants under the leadership of Julien Fédon in opposition to the British. Mermaid was off Labaye, in company with Favorite, when a British blockhouse came under attack from a battery that the rebels had erected. Otway led a landing party of seamen and marines that stormed the battery and destroyed it. Soon after, a large contingent of British troops landed near Labaye. At the same time two French vessels, under British colours, arrived with French troops from Saint Lucia. The British general wished to withdraw, but Otway declined to permit him to do so. Instead, Otway rode up a hill on which there were some field guns that he ordered to fire on the French vessels. The battery commander did so, with the result that the French vessels withdrew, having failed to land their troops. Favorite pursued the French vessels but could not keep up after losing her topmast. The British troops then attacked and captured Pilot Hill.

On 22 July Mermaid and Favorite recaptured the sloop Two Sisters.