Cyprian Southack (1662 - 27 March 1745) was an English cartographer and colonial naval commander. Born in London to a British Navy captain, he came to New England in the 1680s, where he established a reputation for his seamanship and his chart-making skills. The charts he made of the coast of northeastern North America were among the most accurate of their time. He engaged in privateering activities during King William's War in the 1690s, and was hired by the Province of Massachusetts Bay as captain of its armed vessel, the Province Galley. In that role he participated in several military actions during Queen Anne's War, including relieving present-day Portland, Maine from attack before joining Benjamin Church's 1704 raids of Acadia, and the 1707 and 1710 Sieges of Port Royal. He was asked by Admiral Hovenden Walker to pilot his 1711 expedition to Quebec up the Saint Lawrence River, but refused, disclaiming detailed knowledge of that river. (Walker's expedition ended disastrously, suffering more than 800 deaths when parts of the fleet foundered on rocks near the mouth of the Saint Lawrence.)
After Queen Anne's War Southack continued in a variety of public service positions, including a seat on the Nova Scotia Council.
A storm on the night of 26 April 1717 destroyed The Whydah Gally, flagship of the notorious pirate Samuel "Black Sam" Bellamy, on the shoals of Cape Cod. Within days, Southack was sent to the wreck site by Massachusetts Bay Governor Samuel Shute, to recover anything of value. He was given specific orders to take from the townsfolk anything they may have taken from the wreck. According to his several letters to the governor, the entire community refused to cooperate, and the coroner even stuck him with the bill after burying 102 bodies washed ashore from the wreck. he informed the governor that, although he was able to see parts of the Whydah on the sandbar some 500 feet from shore, his week-long efforts to recover anything of value from the wreck were repelled by deadly waves and rip currents cause by the shoals. His letters to the governor and his map of New England, upon which he wrote the location of the Whydah, was instrumental in explorer Barry Clifford's discovery and ongoing recovery of the Whydah's artifacts and treasures.
- namesake of Phillips Street - Southack Street and Southack Court, Beacon Hill, Boston
- Chard, Donald. "Biography of Cyprian Southack". Dictionary of Canadian Biography Online. Retrieved 22 August 2011.
- THE WHYDAH PIRATE MUSEUM, Historian Kenneth J. Kinkor, Docent Jim Cunningham
- Clifford, Barry, EXPEDITION WHYDAH
- Clifford, Barry, THE PIRATE PRINCE
- Southack, Cyprian, circa 1717, An Actual Survey of the Sea Coast from New Your to the Isle of Cape Briton