John Gregory Dunne (May 25, 1932 – December 30, 2003) was an American writer. He began his career as a journalist for Time magazine before expanding into writing criticism, essays, novels, and screenplays. He often collaborated with his wife, Joan Didion.
 Dunne was born in Hartford, Connecticut, and was a younger brother of author Dominick Dunne. He was the son of Dorothy Frances (née Burns) and Richard Edwin Dunne (1894–1946), a hospital chief of staff and heart surgeon. Dunne was the fifth of six children. His maternal grandfather, Dominick Francis Burns (1857–1940), founded the Park Street Trust Company.
 The young Dunne developed a severe stutter and took up writing to express himself. He learned to manage it by observing others. He attended the Portsmouth Priory School and graduated from Princeton University in 1954, where he was member of Tiger Inn.
 Dunne started working as a journalist in New York City for Time magazine. He credited the political essayist Noel Parmentel as a mentor in many ways.
 In the late 1950s, he met Joan Didion in New York City, where she was an editor at Vogue. In a 2005 interview, Didion recalled, "We amused each other and I thought he was smart. He knew a lot of stuff that I didn't know, like politics and history. I had managed to go through school without learning much except a lot of poems." He invited her to travel to Connecticut one weekend in 1963 to visit his family: New England Irish Catholic, with six children. Didion said she "liked the set-up, liked being there, and liked him."
 After they married in 1964, the couple moved to a remote house on the California coast; Didion worked on a novel to follow her debut Run, River, and Dunne on a book about the California grape pickers' strike. They wrote a jointly bylined column for the Saturday Evening Post magazine for years.
 Dunne and Didion gradually picked up writing work from book publishers and magazines, traveled together on journalism assignments, and established a working pattern that served for the next 40 years. They had a constant advising, consulting, and editing collaboration. Critically acclaimed bestselling books followed for each, including Dunne's The Studio, his nonfiction account of 20th Century Fox.
 They also collaborated on a series of screenplays, including The Panic in Needle Park (1971), A Star Is Born (1976), and True Confessions (1981), an adaptation of Dunne's novel of the same name. He wrote a nonfiction book about Hollywood, Monster: Living Off the Big Screen.
 As a literary critic and essayist, Dunne was a frequent contributor to The New York Review of Books. His essays were collected in two books, Quintana & Friends (1980) and Crooning (1990).
 He wrote several novels, among them True Confessions, based loosely on the Black Dahlia murder, and Dutch Shea, Jr.. He was the writer and narrator of the 1990 PBS documentary L.A. is It with John Gregory Dunne, in which he guided viewers through Los Angeles's cultural landscape.
 Dunne and Didion later moved to Manhattan. He died there of a heart attack on December 30, 2003. His final novel, Nothing Lost, which was in galleys at the time of his death, was published in 2004.
 Dunne married Didion on January 30, 1964, at Mission San Juan Bautista in California. He was 31 and she 29. They contemplated filing for divorce in 1969, as Didion famously wrote in one of her essays.
 Unable to have children, in 1966 they adopted a baby at birth and named her Quintana Roo, after the Mexican state. Quintana died in 2005 after a series of illnesses.
 Dunne was uncle to actors Griffin Dunne (who co-starred in An American Werewolf in London) and Dominique Dunne (who co-starred in Poltergeist).
 Didion wrote and published The Year of Magical Thinking (2005), a memoir of the year following his death, during which their daughter was seriously ill. It won critical acclaim and the National Book Award.