HMS Leopard was a 50-gun Portland class fourth rate of the Royal Navy. She served during the French Revolutionary and Napoleonic Wars, and was notable for the actions of her captain in 1807, which were emblematic of the tensions that later erupted in the War of 1812 between Britain and America. She was wrecked in 1814.

In 1603 all English warships with a complement of fewer than 160 men were known as 'small ships'. In 1625/26 to establish pay rates for officers, a six-tier naval ship rating system was introduced. These small ships were divided into three tiers: fourth-, fifth- and sixth-rates. Up to the end of the 17th century, the number of guns and the complement size were adjusted until the rating system was actually clarified. A 'fourth-rate' was nominally a ship of over thirty guns with a complement of 140 men.