Nancy Kissinger, the wife of former Secretary of State Henry A. Kissinger, who shared his whirlwind life of international diplomacy — and then of tarnished celebrity, as a controversial elder statesman — for half a century, died on Thursday at her home in South Kent, Conn. She was 92.

Her death was announced by her family.

Politically savvy, well versed in global issues and fiercely protective of her husband’s name, Mrs. Kissinger traveled widely with him on diplomatic missions after their 1974 marriage. And when Mr. Kissinger stepped down three years later, they became a familiar Washington couple at state dinners, embassy parties and Republican White House receptions.

The Kissingers were also among the most visible couples in New York City, their principal residence, attending museum openings, fashion shows by Bill Blass and Oscar de la Renta, and charity fund-raisers. Since the early 1980s, their summer and weekend retreat from social obligations had been a 300-acre estate in South Kent.

“To the men and women who know her well,” The New York Times quoted one friend as saying after the wedding, “Mrs. Kissinger is an intelligent, capable and warm woman, with a great deal of charm, a good sense of humor and an iron sense of integrity.”

Mrs. Kissinger’s glamorous life was hardly devoid of trouble, and some of it had to do with her husband’s hotly disputed reputation. As secretary of state from 1973 to 1977 under Presidents Richard M. Nixon and Gerald R. Ford, Mr. Kissinger pioneered the policy of détente with the Soviet Union; orchestrated the postwar opening of relations with China; engaged in shuttle diplomacy in the Middle East to end the Arab-Israeli war of 1973, also known as the Yom Kippur War; and helped negotiate the Paris Peace Accords, ending American involvement in the Vietnam War, for which he shared the Nobel Peace Prize.

For all his honors, he remained a polarizing figure, accused by journalists and human rights activists of war crimes for supporting the bombing of Hanoi and an invasion of Cambodia during the Vietnam War; for encouraging a military coup against the socialist government of Salvador Allende in Chile; and for signaling a green light to an Argentine military junta for its “dirty war” against dissidents.

In 1982, walking through a terminal at Newark International Airport, the Kissingers were accosted by Ellen Kaplan, a follower of Lyndon H. LaRouche, a cult leader with both Marxist and right-wing associations. She shouted insults at both Kissingers, and witnesses said that Mrs. Kissinger grabbed the heckler by the throat and threatened to throttle her.

Months later, in a two-hour trial in Newark Municipal Court, Mrs. Kissinger testified that she had been escorting her husband to Boston for a triple-bypass heart operation and that he was under a doctor’s orders to avoid “upset of any kind.” The judge dismissed a misdemeanor charge of simple assault against Mrs. Kissinger, saying that there had been no bodily injury.

In the decade before their marriage, his second, Mr. Kissinger dated the film stars Jill St. John, Liv Ullmann, Shirley MacLaine, Marlo Thomas and others. But his most frequent companion was Nancy Maginnes.

The wedding of Ms. Maginnes, 39, and Henry Kissinger, 50, took place in Arlington, Va., on March 30, 1974, and while it was attended by only a handful of guests and not disclosed until it was over, it was one of the most heavily covered social events of the year. The Times published the news at the top of Page 1 and followed it with a detailed profile of the bride.

She was a foreign policy specialist for the Commission on Critical Choices for Americans, a creation of former Gov. Nelson A. Rockefeller of New York. Mr. Rockefeller had been the bride’s employer and Mr. Kissinger’s friend and political ally for years, and had introduced them at Harvard, where Mr. Kissinger was teaching and Ms. Maginnes became one of his students.

Mr. Kissinger’s 15-year first marriage to Ann Fleischer had ended in divorce in 1964. They had two children, who both attended the wedding, along with the bride’s brother David and her mother, Agnes Maginnes. Mr. Kissinger’s brother, Walter, and his wife were also there, as was Carlyle Maw, a State Department legal adviser.

After the brief civil ceremony, performed by Judge Francis Thomas Jr. of Arlington County Court, the newlyweds flew in Mr. Rockefeller’s private jet to Acapulco, Mexico, for a 10-day honeymoon. A dozen Secret Service agents, 20 Mexican police officers and 40 journalists shadowed their every move. Sailing aboard a 30-foot sloop on Acapulco Bay, Mr. Kissinger kept a protective arm around his new wife, as a motorboat filled with the press corps followed.

They made a striking couple, not least because the ash-blond, chain-smoking Mrs. Kissinger was nearly six feet tall, while her husband, recognized around the world, was only 5-foot-8. But friends said that they were a good match, intellectually and emotionally, and described them as inseparable.

Two months after the honeymoon, Mrs. Kissinger demonstrated her ambassadorial panache by joining her husband’s ongoing shuttle diplomacy in the Middle East, standing for photo ops with Arab and Israeli leaders in various capitals, and attending Mr. Kissinger’s airborne news briefings in her stockinged feet. Her presence was highlighted in Israeli, Arab and American newspapers.

That autumn, she accompanied Mr. Kissinger to the Soviet Union for his talks with the Communist leader Leonid Brezhnev on cuts to strategic nuclear arms, and then flew to New Delhi on the second leg of a three-week diplomatic trip to more than a dozen countries. Friends said her poise helped to hide the anxieties that landed her in a hospital with ulcers soon after their return.

In 2009, Mrs. Kissinger testified in a criminal court case in New York against Anthony D. Marshall, the son of her friend the philanthropist Brooke Astor, who had died two years before. Mr. Marshall had been charged with defrauding his mother’s estate of millions by inducing her to change her will in his favor after her mental capacity had faded. Mr. Marshall was convicted and sentenced to a prison term.

Nancy Sharon Maginnes was born in Manhattan on April 13, 1934, the third child and only daughter of Albert B. Maginnes and Agnes (McKinley) Maginnes. Her father, a former pro football player, was a trusts and estates lawyer in White Plains, N.Y., where Nancy and her two brothers grew up.

She graduated from the Masters School in Dobbs Ferry, N.Y., in 1951, and from Mount Holyoke College in 1955 with a bachelor’s degree in history. She returned to the Masters School for two years to teach history and then took postgraduate courses at the University of California, Berkeley.

In 1964, she went to work for Mr. Kissinger on a Rockefeller task force and, fascinated by foreign affairs, took a job with the Rockefeller Brothers Fund after Mr. Kissinger left to join the Nixon administration in 1969.

The Kissingers had no children. Mr. Kissinger died in 2023. Mrs. Kissinger’s brother Bristol died in the early 1980s, and her brother David, in 2020. She is survived by two stepchildren, Elizabeth Vandermark and David Kissinger, and five step-grandchildren.

Mrs. Kissinger was never officially an American diplomat. But her omnipresence made her as recognizable to some around the globe as presidents and cabinet secretaries. In 2007, when a reporter for The Times entered a shop in Damascus, Syria, the owner pointed to photos on the wall of well-known figures who had bought his furnishings and fabrics.

“That’s Jimmy Carter,” he said, “that’s Warren Christopher, and that’s Nancy Kissinger.”

Ash Wu contributed reporting.