HMS Hyacinth was an 18-gun ship-sloop of the Cormorant class in the Royal Navy, launched in 1806 at Great Yarmouth. In 1810 she was reclassed as a 20-gun Post-ship (but without being re-armed). She was again re-rated as 24 guns in 1817. Hyacinth took part in some notable actions on the coast of Spain, one of which earned qualified in 1847 for the Naval General Service Medal. She was broken up in 1820.
On 21 April 1807 Hyacinth captured the Frau Justina. Then on 15 August 1807 Hyacinth, under Commander John Davie, captured the Zeenymph. That same day Hyacinth was in company with Forrester and Flora when Flora captured the fishing vessels Hoop, Nepthun and Hoffnung. Nine days later Hyacinth and Vestal were in company with Flora when Flora captured the St. Sylvester.