William Smith (1790–1847) was the English captain born in Blyth, Northumberland, who discovered the South Shetland Islands, an archipelago off the Graham Land in Antarctica. His discovery was the first ever made south of 60° south latitude, in the present Antarctic Treaty area.
In 1819, while sailing cargo on the Williams from Buenos Aires to Valparaíso, he sailed further south round Cape Horn in an attempt to catch the right winds. On 19 February 1819 he spotted the new land at 62° south latitude and 60° west longitude, but did not land on it. The naval authorities did not believe his discovery, but on a subsequent trip on 16 October he landed on the largest of the islands. He named the island King George Island and the archipelago South Shetland Islands in honour of the Shetland Islands which are to the north of Scotland. At the beginning of the following year, 1820, the Williams was chartered by the Royal Navy, and dispatched with Smith and Lieutenant Edward Bransfield on board to survey the newly discovered islands, discovering also the Antarctic Peninsula in the process.