Prevost Island is an island in the southern Gulf Islands of the South Coast of British Columbia, Canada, located east of Ganges Harbour and midway between the southeastern extremity of Salt Spring Island (W) and the southern end of Galiano Island (E). The island was named for James Charles Prevost, who was British Commissioner for the San Juan Island boundary dispute of 1859-1870 and captain of HMS "Satellite". Prevost Harbor on nearby Stuart Island, Washington is also named after Prevost and Satellite Island, within Prevost Harbor, is named after his ship. The "Satellite" played a critical role in the Lamalcha War in the same area in 1863.