John Gregory Dunne (25 May 1932 - 30 December 2003) was an American novelist, screenwriter and literary critic.
He was born in Hartford, Connecticut, and was a younger brother of author Dominick Dunne. He suffered from a severe stutter and took up writing to express himself: eventually he learned to speak normally by observing others. He graduated from Princeton University in 1954 and worked as a journalist for Time magazine. He married novelist Joan Didion on January 30, 1964, and they became collaborators on a series of screenplays, including A Star Is Born (1976) and True Confessions (1981).
The couple has one child, a daughter, Quintana Roo Dunne Michael, who was adopted at birth.
As a literary critic, he frequently was a contributor to The New York Review of Books.
He died in Manhattan of a heart attack. His final work, in galleys at the time of his death, will be published posthumously.
He was uncle to actors Griffin Dunne and Dominique Dunne.