William Haddad (July 25, 1928 – April 30, 2020) was an American political operative, lobbyist, and journalist who held a series of high-profile jobs during his lifetime. He is most known for being an aide to the Kennedy Family, during which he helped launch the Peace Corps with R. Sargent Shriver, worked in the 1960 presidential campaign of John F. Kennedy and the 1968 presidential campaign of Robert F. Kennedy. He also assisted prominent Democratic Party figures such as Mario Cuomo and Estes Kefauver and led the fight for affordable medicine as a lobbyist and businessman.