Hunt was born in Hamburg, New York, United States, of English and Welsh descent. An alumnus of Nichols School in Buffalo, New York and a 1940 graduate of Brown University, Hunt during World War II served in the U.S. Navy on the destroyer USS Mayo, United States Army Air Forces, and finally, the Office of Strategic Services (OSS) which he worked for in China. During and after the war, he also wrote several novels under his own name ... East of Farewell (1942), Limit of Darkness (1944), Stranger in Town (1947), Bimini Run (1949) (with a hero named "Hank Sturgis"), and The Violent Ones (1950) ... and, more famously, several spy and hardboiled novels under an array of pseudonyms, including Robert Dietrich, Gordon Davis and David St. John. Hunt won a Guggenheim Fellowship for his writing in 1946.

Warner Bros. had just bought rights to Hunt's novel Bimini Run when he joined the CIA in October 1949 as a political action specialist in what came to be called their Special Activities Division. He became station chief in Mexico City in 1950, and supervised William F. Buckley, Jr., who worked for the CIA in Mexico during the period 1951—1952. Buckley and Hunt remained lifelong friends.

In Mexico, Hunt helped devise Operation PBSUCCESS, the covert plan to overthrow Jacobo Arbenz, the elected president of Guatemala. Following assignments in Japan and as station chief in Uruguay, Hunt was assigned to forge Cuban exile leaders in the United States into a broadly representative government-in-exile that would, after the Bay of Pigs Invasion, form a provisional government to take over Cuba. The failure of the invasion damaged his career.

After the Bay of Pigs, Hunt became a personal assistant to Allen Dulles. Tad Szulc states that Hunt was asked to assist Dulles in writing a book, The Craft of Intelligence, that Dulles wrote following his involuntary retirement in 1961. The book was published in 1963.

Hunt told the Senate Watergate Committee in 1973 that he served as the first Chief of Covert Action for the CIA's Domestic Operations Division. He told the New York Times in 1974 that he spent about four years working for the division, beginning shortly after it was set up, by the Kennedy Administration in 1962, over the "strenuous opposition" of Richard Helms and Thomas H. Karamessines. He said that the division was assembled shortly after the Bay of Pigs operation, and that "many men connected with that failure were shunted into the new domestic unit." He said that some of his projects from 1962 to 1966, which dealt largely with the subsidizing and manipulation of news and publishing organizations, "did seem to violate the intent of the agency's charter."

According to Tad Szulc, Hunt was assigned to temporary duty as the acting CIA station chief in Mexico City for the period of August and September 1963, at the time of Lee Harvey Oswald's alleged visit there. In his 1978 testimony, however, Hunt denied having been in Mexico at all between 1961 and 1970.

Hunt was undeniably bitter about what he saw as President John F. Kennedy's lack of spine in overturning the Fidel Castro regime. In his semi-fictional autobiography, Give Us This Day, he wrote: "The Kennedy administration yielded Castro all the excuse he needed to gain a tighter grip on the island of Jose Marti, then moved shamefacedly into the shadows and hoped the Cuban issue would simply melt away."Disillusioned, he retired from the CIA on May 1, 1970, and went to work for the Robert R. Mullen Company, which cooperated with the CIA. Hunt obtained a Covert Security Approval to handle the firm's affairs during Mullen's absence from Washington. The following year, he was hired by Charles Colson, chief counsel to President Richard Nixon, and joined the President's Special Investigations Unit (alias White House Plumbers).

Hunt's first assignment for the White House was a covert operation to break into the Los Angeles office of Daniel Ellsberg's psychiatrist, Dr. Lewis J. Fielding. In July 1971, Fielding had refused an FBI request for psychiatric data on Ellsberg. Hunt and Liddy cased the building in late August. The burglary, on September 3, 1971, was not detected, but no Ellsberg files were found.

Also in the summer of 1971, Colson authorized Hunt to travel to New England to seek potentially scandalous information on Senator Edward Kennedy. Hunt sought and used CIA disguises and other equipment for the project.

Hunt's White House duties included assassinations-related disinformation. In September 1971, Hunt forged and offered to a Life magazine reporter top-secret State Department cables designed to prove that President Kennedy had personally and specifically ordered the assassination of Ngo Dinh Diem and his brother Ngo Dinh Nhu. Hunt told the Senate Watergate Committee in 1973 that he had fabricated the cables to show a link between President Kennedy and the assassination of Diem, a Catholic, to estrange Catholic voters from the Democratic party, after Colson suggested he "might be able to improve upon the record."

According to Seymour Hersh, writing in The New Yorker, Nixon White House tapes show that after presidential candidate George Wallace was shot on May 15, 1972, Nixon and Colson agreed to send Hunt to the Milwaukee home of the gunman, Arthur Bremer, to place McGovern presidential campaign material there. The intention was to link Bremer with the Democrats. Hersh writes that, in a taped conversation, "Nixon is energized and excited by what seems to be the ultimate political dirty trick: the FBI and the Milwaukee police will be convinced, and will tell the world, that the attempted assassination of Wallace had its roots in left-wing Democratic politics." Hunt did not make the trip, however, because the FBI had moved too quickly to seal Bremer's apartment and place it under police guard.

Hunt organized the bugging of the Democratic National Committee at the Watergate office building.

A few days after the break-in, Nixon was recorded saying, to H. R. Haldeman, "This fellow Hunt, he knows too damn much."

[V]ery bad, to have this fellow Hunt, ah, you know, ah, it's, he, he knows too damn much and he was involved, we happen to know that. And that it gets out that the whole, this is all involved in the Cuban thing, that it's a fiasco, and it's going to make the FB, ah CIA look bad, it's going to make Hunt look bad, and it's likely to blow the whole, uh, Bay of Pigs thing which we think would be very unfortunate for CIA and for the country at this time, and for American foreign policy, and he just better tough it and lay it on them.

Hunt and fellow operative G. Gordon Liddy, along with the five arrested at the Watergate, were indicted on federal charges three months later.

Hunt's wife, Dorothy, was killed in the December 8, 1972 plane crash of United Airlines Flight 553 in Chicago. Congress, the Federal Bureau of Investigation (FBI), and the National Transportation Safety Board (NTSB) investigated the crash, and found it to be an accident caused by crew error. Over $10,000 in cash was found in Dorothy Hunt's handbag in the wreckage.

Hunt eventually spent 33 months in prison on a conspiracy charge, and said he was bitter that he was sent to jail while Nixon was allowed to resign.

Give Us This Day, Hunt's book on the Bay of Pigs Invasion, was published late in 1973. In the book's foreword, he commented on the assassination of President John F. Kennedy as follows:

Once again it became fashionable to hold the city of Dallas collectively responsible for his murder. Still, and let this not be forgotten, Lee Harvey Oswald was a partisan of Fidel Castro, and an admitted Marxist who made desperate efforts to join the Red Revolution in Havana. In the end, he was an activist for the Fair Play for Cuba Committee. But for Castro and the Bay of Pigs disaster there would have been no such "Committee." And perhaps no assassin named Lee Harvey Oswald.

On November 3, 1978, Hunt gave a security-classified deposition for the House Select Committee on Assassinations (HSCA). The Assassination Records Review Board (ARRB) released the deposition in February 1996. The House Select Committee on Assassinations concluded that there was a conspiracy to kill John F. Kennedy. They came to this conclusion because of a recording of the assassination from a Dallas Police officers mic that was stuck on the ON position. The scientific acoustical evidence establishes a 95% high probability that there was a second gunmen, besides Oswald, in the infamous grassy knoll area. The Committee could not determine who the gunman was and what the extent of the conspiracy was. In 2005, an article in Science & Justice by Ralph Linsker, Richard Garwin, Herman Chernoff, Paul Horowitz, and Norman Foster Ramsey, Jr. re-analyzed the acoustic synchronization evidence, supporting the NAS report's finding that the sounds alleged to be gunshots occurred about a minute after the assassination.Two newspaper articles published a few months before the deposition stated that a 1966 CIA memo linking Hunt to the assassination of President Kennedy had recently been provided to the HSCA. The first article, by Victor Marchetti...author of the book The CIA and the Cult of Intelligence (1974)...appeared in the Liberty Lobby newspaper The Spotlight on August 14, 1978. According to Marchetti, the memo said in essence, "Some day we will have to explain Hunt's presence in Dallas on November 22, 1963." He also wrote that Hunt, Frank Sturgis, and Gerry Patrick Hemming would soon be implicated in a conspiracy to kill John F. Kennedy.

The second article, by Joseph J. Trento and Jacquie Powers, appeared in the Wilmington, Delaware Sunday News Journal six days later. It alleged that the purported memo was initialed by Richard Helms and James Angleton and showed that, shortly after Helms and Angleton were elevated to their highest positions in the CIA, they discussed the fact that Hunt had been in Dallas on the day of the assassination and that his presence there had to be kept secret. However, nobody has been able to produce this supposed memo, and theUnited States President's Commission on CIA activities within the United States determined that Hunt had been in Washington, D.C. on the day of the assassination.

Hunt sued Liberty Lobby...but not the Sunday News Journal...for libel. Liberty Lobby stipulated, in this first trial, that the question of Hunt's alleged involvement in the assassination would not be contested. Hunt prevailed and was awarded $650,000 damages. In 1983, however, the case was overturned on appeal because of error in jury instructions. In a second trial, held in 1985, Mark Lane made an issue of Hunt's location on the day of the Kennedy assassination. Lane successfully defended Liberty Lobby by producing evidence suggesting that Hunt had been in Dallas. He used depositions from David Atlee Phillips, Richard Helms, G. Gordon Liddy, Stansfield Turner, and Marita Lorenz, plus a cross-examination of Hunt. On retrial, the jury rendered a verdict for Liberty Lobby. In spite of Lane's claim that he convinced the jury that Hunt was a JFK assassination conspirator, most of the jurors who were interviewed by the media said they disregarded the conspiracy theory and judged the case (according to the judge's jury instructions) on whether the article was published with "reckless disregard for the truth." Lane outlined his theory about Hunt's and the CIA's role in Kennedy's murder in a 1991 book, Plausible Denial.

Many people that believe JFK was assassinated as a result of a conspiracy have suggested that two of the three tramps that marched through Dealey Plaza in the wake of the assassination to be Howard Hunt and Frank Sturgis, although several other men, Charles Harrelson for example, were also identified as tramps. The mystery was thought to be solved in the early 1990s when researcher Mary LaFontaine discovered documents identifying the men as Harold Doyle, John Forester Gedney, and Gus W. Abrams. Both the F.B.I. and independent researchers confirmed the identifications.

The Mitrokhin Archive by Christopher Andrew and Vasili Mitrokhin, on the evidence supplied by Mitrokhin's transcribed versions of Top Secret KGB files, alleges that the Soviet Union was principal in falsely connecting E. Howard Hunt to the Kennedy Assassination. Those allegations contradict the House Select Committee on Assassinations final report. The Committee concluded that there was no evidence to prove Soviet Union/KGB involvement. Mitrokhin alleges, for example, that the KGB recruited and provided secret financial support for Mark Lane and other conspiracy theorist authors, including Carl Aldo Marzani and Joachim Joesten.

Hunt was also the addressee of a letter, purportedly from Oswald, dated two weeks before the assassination. Andrew and Mitrokhin state that the letter was a hoax, carefully created by the KGB to implicate Hunt and the CIA, based upon a belief that Hunt had been in Dallas on the day of the assassination. The letter was accepted as genuine by Oswald's widow and left the House Select Committee on Assassinations (1978) unable to verify or discredit its authenticity. Eventually it appeared in the American press, though some assumed the "Mr. Hunt" to whom it was addressed to be the oil magnate H. L. Hunt, whom the Kremlin first suspected of plotting the assassination.

Hunt was a prolific author, primarily of spy novels. He lived in Biscayne Park, Florida.

A fictionalized account of Hunt's role in the Bay of Pigs operation appears in Norman Mailer's 1991 novel Harlot's Ghost.

Canadian journalist David Giammarco interviewed Hunt for the December 2000 issue of Cigar Aficionado magazine. Writing later in Controversy magazine, Giammarco related an interview with a "former high-ranking CIA officer" in Miami who was "intrinsically involved in the CIA's disastrous Bay of Pigs invasion of April 1961 and the many plots to kill Castro." The subject, whose description closely resembles Hunt's, is not identified by name. However, the individual reportedly told Giammarco that "he would confess to his part in the JFK assassination for a price tag of $14 million." E. Howard Hunt also wrote the foreword to David Giammarco's best-selling book "For Your Eyes Only: Behind the Scenes of the James Bond Films" (ECW Press, 2002). Over the course of their long friendship, the elder spy Hunt apparently shared many secrets with David Giammarco. However, the exact details have not been publicly disclosed by Giammarco.

During the last few years and months of Hunt's life he disclosed to his son, Saint John Hunt, through audio recordings, discussions, and through writings that he, and several others were involved in the conspiracy to kill President John F. Kennedy. He even gave the codename the conspirators gave for the operation, "the Big Event." The other alleged conspirators include Cord Meyer, David Sánchez Morales, William King Harvey, a French gunman who worked for the Mafia, and Lyndon B. Johnson; Hunt's allegations, however, are generally considered unsubstantiated because what he said has not been proven by any official investigation after his deathbed confession in 2007. Cord Meyer and Bill Harvey were in the CIA. David Morales was unofficially in the CIA. Hunt died on January 23, 2007 in Miami, Florida of pneumonia and is buried in Prospect Lawn Cemetery, Hamburg, New York. Hunt's memoir American Spy: My Secret History in the CIA, Watergate, and Beyond was published by John Wiley & Sons in March 2007.

Nonfiction

• Give Us This Day: The Inside Story of the CIA and the Bay of Pigs Invasion...by One of Its Key Organizers (1973)
• Undercover: memoirs of an American secret agent / by E. Howard Hunt (1974)
• For Your Eyes Only: Behind the Scenes of the James Bond Films / by David Giammarco; foreword by E. Howard Hunt (2002)
• American spy: my secret history in the CIA, Watergate, and beyond / E. Howard Hunt; with Greg Aunapu; foreword by William F. Buckley, Jr. (2007)

Novels published as Howard Hunt or E. Howard Hunt:

• East of Farewell (1943)
• Limit of darkness, a novel by Howard Hunt (1944)
• Stranger in town (1947)
• Calculated risk: a play / by Howard Hunt (1948)
• Maelstrom / Howard Hunt (1948)
• Bimini run / by Howard Hunt (1949)
• The Violent Ones (1950)
• Berlin ending; a novel of discovery (1973)
• Hargrave deception / E. Howard Hunt (1980)
• Gaza intercept / E. Howard Hunt (1981)
• Cozumel / E. Howard Hunt (1985)
• Kremlin conspiracy / E. Howard Hunt (1985)
• Guadalajara / E. Howard Hunt (1990)
• Murder in State / E. Howard Hunt (1990)
• Body count / E. Howard Hunt (1992)
• Chinese Red / by E. Howard Hunt (1992)
• Mazatlán / E. Howard Hunt (1993) (lists former pseudonym P. S. Donoghue on cover)
• Ixtapa / E. Howard Hunt (1994)
• Islamorada / E. Howard Hunt (1995)
• Paris edge / E. Howard Hunt (1995)
• Izmir / E. Howard Hunt (1996)
• Dragon teeth: a novel / by E. Howard Hunt (1997)
• Guilty knowledge / E. Howard Hunt (1999)
• Sonora / E. Howard Hunt. (2000)

As Robert Dietrich:

• Cheat (1954)
• Be My Victim (1956)
• Murder on the rocks: an original novel (1957)

As P. S. Donoghue:

• Dublin Affair (1988)
• Sarkov Confession: a novel (1989)
• Evil Time (1992)

As David St. John

• Hazardous Duty (1966)
• Mongol Mask (1968)
• Sorcerers (1969)
• Diabolus (1971)
• Coven (1972)

As Gordon Davis:

• I Came to Kill (1953)
• House Dick (1961)
• Counterfeit Kill (1963)
• Ring Around Rosy (1964)
• Where Murder Waits (1965)

As John Baxter:

• A Foreign Affair