Sullivan Island is an island in Lynn Canal, southwest of Chilkat Island, Southeast Alaska, United States. It was named in 1869 by Commander R.W. Meade, USN, for the master of the schooner Louisa Downs, which had wrecked on the island in 1867. The Tlingit name for the island is "Schikuk". The first European to discover and chart the island was Joseph Whidbey, master of the HMS Discovery during George Vancouver's 1791-95 expedition, in 1794.

Sullivan's Island is a town and island in Charleston County, South Carolina, United States, at the entrance to Charleston Harbor, with a population of 1,791 at the 2010 census. The town is part of the Charleston metropolitan area.