Pevensey is a small town in East Sussex in southern England on the English Channel, with a population of approximately 3,000. The modern settlement, now known as Pevensey Bay, is a seaside resort. The old village of Pevensey lies two miles to the northeast, on the eastern side of an old fortress now known as Pevensey Castle.

Pevensey was founded as a Roman fort built about A.D. 250 to defend the coast against incursions by the Franks and Alemanni. At that time, the fortress stood on a small island off the shore, which the Romans called "Anderida," but the sea has since retreated, leaving the site well inland.

When the Romans finally abandoned Britain for good in A.D. 408, the Saxons occupied the site, naming it "Pefe Ie," meaning "Pefe Island," from which the modern name "Pevensey" derives.

Historians believe that William the Conqueror landed at Pevensey when he invaded England in 1066. The old Roman fortress was later the site of a large Norman castle, and today ruins of both the Roman and Norman walls can still be found at the site. In the Early Modern Period, Pevensey was a member of the Cinque Ports.