HMS Bacchus was a schooner of the Adonis class of the Royal Navy during the Napoleonic War. She was built at Bermuda using Bermudan cedar and completed in mid-1806. A report dated 9 May 1806 stated that Bacchus was three to six weeks away from completion. Still, Bacchus was commissioned under Lieutenant George Skinner and on 9 June was in company with Tartar when Tartar captured the French brig Observateur after a chase and a slight exchange of gunfire. Observateur, of 18 guns, though pierced for 20, and with a crew of 104 men, was under the command of Captain "Crozier" (Croizé). She had left Cayenne on 15 March provisioned for a cruise of four months and in company with the French brig Argus, but had not taken anything. The Royal Navy took her into service as HMS Observateur.