Gore Vidal, the elegant, acerbic all-around man of letters who presided with a certain relish over what he declared to be the end of American civilization, died Tuesday at his home in Los Angeles. He was 86.

The cause was complications of pneumonia, his nephew Burr Steers said.

Vidal was, at the end of his life, an Augustan figure who believed himself to be the last of a breed, and he was probably right. Few American writers have been more versatile or gotten more mileage from their talent.

He published some 25 novels, two memoirs and several volumes of stylish, magisterial essays. He also wrote plays, TV dramas and screenplays. For a while he was even a contract writer at MGM. And he could always be counted on for a spur-of-the-moment aphorism, putdown or sharply worded critique of U.S. foreign policy.

Vidal loved conspiracy theories, especially the ones he imagined himself at the center of, and he was a famous feuder; he engaged in celebrated on-screen wrangles with Norman Mailer, Truman Capote and William F. Buckley Jr. Vidal did not lightly suffer fools — a category that for him comprised a vast swath of humanity — and he was not a sentimentalist or a romantic. “Love is not my bag,” he said.

By the time he was 25, he had had more than 1,000 sexual encounters with both men and women, he boasted in his memoir “Palimpsest.” Vidal tended toward what he called “same-sex sex,” but frequently declared that human beings were inherently bisexual, and that labels like gay or straight were arbitrary and unhelpful. For 53 years, he had a live-in companion, Howard Austen, but the secret of their relationship, he often said, was that they had never slept together.

The early years

Eugene Luther Gore Vidal Jr. was born on Oct. 3, 1925, at the U.S. Military Academy at West Point, where his father was teaching aeronautics. Vidal Sr. went on to found three airlines, including one that became TWA.

Vidal’s mother, Nina, was an actress and socialite whom he detested and frequently described as a bullying, self-pitying alcoholic. She and Vidal’s father divorced in 1935, and she married Hugh Auchincloss, the stepfather of Jacqueline Kennedy Onassis.

Vidal attended St. Albans School in Washington, where he lopped off his Christian names and became simply Gore Vidal, which he considered more literary-sounding, and where he had an intense romantic and sexual relationship with Jimmie Trimble, one of the school’s best athletes. Trimble’s premature death at Iwo Jima in World War II seemingly made it impossible for Vidal ever to feel the same way about anyone else.

After leaving St. Albans in 1939, Vidal spent a year at the Los Alamos Ranch School in New Mexico before enrolling at Phillips Exeter Academy in New Hampshire. He graduated from Exeter at 17 — only by cheating, he later admitted, on virtually every math exam — and enlisted in the Army, where he became first mate on a freight supply ship in the Aleutian Islands.

He began work on “Williwaw,” a novel set on a troopship and published in 1946 while he was an associate editor at the publishing company E.P. Dutton. In 1948, Vidal published “The City and the Pillar,” which was dedicated to J.T. (Jimmie Trimble), about a handsome, athletic young Virginia man who gradually discovers that he is homosexual. By today’s standards it is tame, but at the time it caused a scandal and was denounced as pornographic.

To make a living, Vidal concentrated on writing for television, then for the stage and the movies.

‘Such fun, such fun’

In the ’60s Vidal returned to writing novels and published three books in fairly quick succession: “Julian” (1964), “Washington, D.C.” (1967) and “Myra Breckenridge” (1968). “Julian,” which some critics still consider Vidal’s best, was a painstakingly researched historical novel about the fourth-century Roman emperor who tried to convert Christians back to paganism. “Washington, D.C.” was a political novel set in the ’40s. “Myra Breckenridge,” Vidal’s favorite among his books, was a campy black comedy about a male homosexual who has gender reassignment surgery.

In the years to come, his greatest successes came with historical novels, especially what became known as his American Chronicles sextet: “Washington, D.C.,” “Burr” (1973), “1876” (1976), “Lincoln” (1984), “Hollywood” (1990) and “The Golden Age” (2000). He turned out to have a particular gift for this kind of writing.

In the opinion of many critics, though, Vidal’s ultimate reputation is apt to rest less on his novels than on his essays, many of them written for The New York Review of Books and collected in several volumes. His collection “The Second American Revolution” won the National Book Critics Circle Award for criticism in 1982. About a later collection, “United States: Essays 1952-1992,” R.W.B. Lewis wrote in The New York Times Book Review that Vidal the essayist was “so good that we cannot do without him,” adding, “He is a treasure of state.”

In 2003, Vidal and his companion, Austen, who was ill, left their Italian villa and moved to the Hollywood Hills to be closer to Cedars-Sinai Medical Center. Austen died later that year.

After his death, Vidal lived alone in declining health himself. He was increasingly troubled by a knee injury he suffered in the war, and used a wheelchair to get around. In November 2009 he made a rare public appearance to attend the National Book Awards in New York, where he was given a lifetime achievement award. He evidently had not prepared any remarks, and instead delivered a long, meandering impromptu speech that was sometimes funny and sometimes a little hard to follow. At one point he even seemed to speak fondly of Buckley, his old nemesis. It sounded like a summing up.

“Such fun, such fun,” he said.