USS Hornet was a 20-gun sloop-of-war of the United States Navy. During the War of 1812, she was the first U.S. Navy ship to capture a British privateer.

Hornet was launched 28 July 1805 in Baltimore and commissioned there on 18 October, Master Commandant Isaac Chauncey in command.

Hornet's design was a compromise between the six original U.S. frigates and coastal gunboats championed by President Thomas Jefferson. The fledgling Navy needed a light-draft vessel that was fast and maneuverable, but also possessing sufficient firepower to deter or defeat enemy ships. Hornet's design is attributed to Josiah Fox, but her builder, William Price, is said to have altered it based on the successful lines of the Baltimore Clipper, of which he had significant experience.

During his time as captain, Chauncey reported significant problems with Hornet's rigging, hindering her overall potential. In response to these reports, Hornet's sister ship, Wasp, constructed at the Washington Navy Yard, had her rigging changed to three masts and afterward reported excellent performance at sea.

Hornet cruised the Atlantic coast until 29 March 1806 when she sailed to join the squadron protecting American commerce from threats of piracy in the Mediterranean. She returned to Charleston, South Carolina on 29 November 1807 and was decommissioned.

Hornet was recommissioned on 26 December 1808. She transported General James Wilkinson to New Orleans, Louisiana, cruised in home waters to enforce the Embargo Act, and carried dispatches to Holland, France, and England. From November 1810 to September 1811, Hornet was rebuilt in the Washington Navy Yard. Based on the success of Wasp, Hornet received a ship-rig with three masts carrying square sails. She also had two additional gun ports fitted, which increased her capacity to 20 guns. Instead of her original eighteen 9-pounder long guns, Hornet was fitted to carry eighteen 32-pounder carronades and two 12-pounder long guns.

At the outbreak of war, Hornet sailed under the command of Master Commandant James Lawrence. It was Hornet that carried the diplomatic messages from Britain, notifying the United States that the Royal Navy would continue impressing alleged deserters from American merchantmen. Lawrence then sailed Hornet with Commodore John Rodgers' Squadron on a raiding voyage to South America. It was during this voyage when the privateer Dolphin was captured on 9 July 1812 — the first prize of the war taken by a naval vessel — which was subsequently recaptured by the British while en route to the United States.

In October, Hornet sailed south with Constitution, under Commodore William Bainbridge, to harass British shipping. In December, Lawrence spotted and blockaded HMS Bonne Citoyenne in the harbor at Salvador, Brazil. When Montague (74 guns) arrived and broke the blockade, Lawrence shifted his efforts to the Caribbean.