HMS Harpy was launched at Liverpool in 1777, the British Royal Navy having purchased her on the stocks.

[1] Harpy shared with some 30 vessels in the prize money for the capture on 4 July 1780 of the French privateer Comte d'Estaing.

[1] In spring 1781, Admiral George Darby sailed a fleet to Gibraltar to relieve the siege for a second time.

On the way the fleet captured Duc de Chartres, the Spanish frigate Santa Leucadia, and the French brig Trois Amis.

Although HMS Cumberland executed the actual capture of Duc de Chartres, the entire British fleet of 42 vessels, including Harpy, shared in the resulting prize money.

[8] Harpy shared with 11 other ships the prize money for Noord Beck, captured on 23 June 1781, and the recapture of Neptune four days later.

[9] She also shared with a number of vessels in the prize money for the Voyageur, captured on 12 August.

[1] Whaler: In August 1785 Lloyd's List reported that Harpy, Marshall, master, was off Whitby, returning from Greenland with one "fish" (whale).

Harpy first appeared in Lloyd's Register in 1786 with J. Marshall, master, J. Dawse, owner, and trade London–Greenland.

Captain John Inskip and Harpy, Hattersley & Co., owners, were at the Downs on 23 October 1788, waiting to sail for the South Seas.

[14][a] Merchantman: On 5 January 1792 Harpy, Wilson, master, sailed from the Downs for Sierra Leone.

Lloyd's List for 4 May 1792 reported that Amy, Patterson, Lapwing, Robinson, Harpy, Wilson, and 15 ships from Halifax, Nova Scotia ha arrived in Sierra Leone.

[5] Capture: In September 1794 a French naval squadron comprising the razee Experiment under the command of lieutenant de vaisseau Arnaud, Vigilance, Félicité, Mutine, Pervie, and Mutine was cruising the West African coast, destroying British factories and shipping.