Colonel William O'Brien, 2nd Earl of Inchiquin, PC (c. 1640 – 16 January 1692), was an Irish military officer, peer and colonial administrator who served as the governor of Tangier from 1675 to 1680 and the governor of Jamaica from 1690 until his death in office in 1692. O'Brien is best known for his long career in the service of the English Crown, serving as a colonial governor in England's overseas possessions in Africa and the West Indies.