William Charles Cole Claiborne was an American politician, best known as the first non-colonial governor of Louisiana. He also has the distinction of possibly being the youngest member of the United States Congress in U.S. history, although reliable sources differ about his age.

William Claiborne also, spelled Cleyburne was an English pioneer, surveyor, and an early settler in the colonies/provinces of Virginia and Maryland and around the Chesapeake Bay. Claiborne became a wealthy merchant and planter, as well as a major political figure in the mid-Atlantic colonies. He featured in disputes between the colonists of Virginia and the later settling of Maryland, partly because of his earlier trading post on Kent Island in the mid-way of the Chesapeake Bay, which provoked the first naval military battles in North American waters. Claiborne repeatedly attempted and failed to regain Kent Island from the Maryland Calverts, sometimes by force of arms, after its inclusion in the lands that were granted by a 1632 Royal Charter to the Calvert family. Kent Island had become Maryland territory after the surrounding lands were granted to Sir George Calvert, first Baron and Lord Baltimore (1579–1632) by the reigning King of England, Charles I.