HMS Hussar was a 38-gun fifth-rate Amazon-class frigate of the Royal Navy. Launched at the end of 1799, the entirety of the frigate's career was spent serving in the English Channel and off the coast of Spain. Hussar primarily served as a convoy escort and cruiser, in which occupation the frigate took several prizes, including the French privateer Le General Bessieres. Towards the end of 1803 Hussar was sent to serve in Sir Edward Pellew's Ferrol squadron. On 8 February 1804 Hussar was returning to England with dispatches when the ship was wrecked off the coast of Île de Sein. The crew attempted to sail for home in a fleet of commandeered boats, but the majority were forced to go into Brest to avoid sinking in bad weather, where they were made prisoners of war.

Hussar was a 38-gun, 18-pounder, fifth-rate Amazon-class frigate. The ship was one of two built to the design, along with the namesake of the class HMS Amazon. The ships were drawn up by the Surveyor of the Navy Sir William Rule, who submitted the design on 19 April 1796. They were an enlarged version of a previous design by Rule, the 38-gun HMS Naiad. Naiad was in turn an expanded version of another, older, Rule ship class, this being the Amazon class designed in 1794.

Hussar was ordered on 15 February 1797 to be built at Woolwich Dockyard by shipwright John Tovery. The ship was originally planned to be named Hyaena, but this was changed on 24 January 1798. Hussar was laid down in August of the latter year, and launched on 1 June 1799 with the following dimensions: 150 feet 3 inches (45.8 m) along the upper deck, 125 feet 8 inches (38.3 m) at the keel, with a beam of 39 feet 6 inches (12 m) and a depth in the hold of 13 feet (4 m). The ship had a draught of 18 feet 1 inch (5.5 m) forward and 19 feet 8 inches (6 m) aft, and measured 1,04288⁄94 tons burthen. The fitting out process was completed in the River Thames on 11 November, with the final cost of construction totalling £29,884.

Hussar's class was described in sailing reports as "fast and very weatherly", as well as being highly manoeuvrable. They were capable of reaching up to 13 knots (24.1 km/h) and showed superior sailing qualities to most other vessels, especially when in a "stiff breeze". The ships were, however, known for "deep and uneasy rolling and pitching", which naval historian Robert Gardiner suggests was because they were built very stiffly.

The frigate had a crew complement of 284, which would later be raised to 300, and held twenty-eight 18-pounder guns on the upper deck. Rule had originally planned for the quarterdeck to hold eight 9-pounder guns and the forecastle to hold a further two, but on 6 May 1797 six 32-pounder carronades were added to the quarterdeck armament and two more to the forecastle. Hussar's armament was changed again on 17 June 1799, with all but two 9-pounders on each of the quarterdeck and forecastle replaced by more carronades. This resulted in a final armament of twelve 32-pounder carronades and two 9-pounder guns on the quarterdeck, and two 32-pounder carronades and two 9-pounder guns on the forecastle, in addition to Hussar's main 18-pounder guns.

Hussar was commissioned by Captain Lord Garlies in November 1799, for service in the English Channel and off the coast of Ireland as part of the Cork Station. Hussar was in company with the 38-gun frigate HMS Loire and 16-gun schooner HMS Milbrook on 17 May 1800 when the three ships recaptured the British merchant ship Princess Charlotte and captured the French schooner La Francoise. Hussar subsequently sailed to Madeira, returning from there on 9 July. The frigate continued to serve off Ireland, escorting a convoy of ships from west India in to England on 31 October. On 9 November a large gale hit the south coast of England, and many ships in the area were driven out to sea by it and badly damaged. Among these casualties was Hussar, which lost all topmasts and the mizzenmast in the gale, and received considerable hull damage, including the loss of the rudder. Hussar was brought into Portsmouth with a hoy rigged behind as a temporary rudder. The ship was docked for repairs, which were completed on 28 November.

Having returned to sea, Hussar continued operating with convoys, escorting the East India Company ships Carnatic, Henry Addington, Nottingham, and Ocean on the first leg of their journey to Calcutta on 8 January 1801. Then on 2 March the frigate captured the French 4-gun privateer Le General Bessieres in the Atlantic Ocean. The French warship had been attempting to sail from Bordeaux to Santo Domingo. Hussar then recaptured the British merchant ship James on 12 April. Later on in the same month Garlies was replaced in command of Hussar by Captain John Giffard, but he in turn gave command over to Captain William Brown soon afterwards. Brown also served in Hussar only briefly, with Captain John Ommanney soon taking over from him on a temporary basis, with the frigate continuing to serve in the English Channel. On 22 May the 54-gun fourth-rate HMS Madras attempted to enter Portsmouth, but grounded on Bembridge Ledge. Hussar joined with the 24-gun post ship HMS Eurydice and together they pulled Madras off without damaging the ship.

Hussar received a refit at Plymouth Dockyard between May and November 1802, and was recommissioned in June by Captain Philip Wilkinson, who had joined the ship in May. The frigate was sent to serve in the North Sea and English Channel. On 10 January 1803 the frigate's gunnery storeroom caught fire while anchored near Sheerness. The fire was close to the ship's magazine and while it did not reach it, some other combustible matter did explode. In reaction to this Hussar's crew ran onto the quarterdeck, from where one small boat was hanging off the rear of the ship. Too many people attempted to board the boat to escape the explosion, causing the davit to break and all in the boat to be thrown into the water. Two master's mates, a midshipman, fourteen seamen, and a woman were drowned. No more explosions on Hussar occurred and Wilkinson was able to stop the fire from spreading or from doing serious damage to the frigate.