William James McGuire (February 17, 1925 in New York City, New York – December 21, 2007 in New Haven, Connecticut) was an American social psychologist known for his work on the psychology of persuasion and for developing Inoculation theory. He was a faculty member at Yale University from 1970 until he retired in 1999, and chaired the psychology department there from 1971 to 1973. He was the editor-in-chief of the Journal of Personality and Social Psychology from 1967 to 1970.