Annenberg, who served briefly as President Reagan's chief of protocol, died early Thursday of natural causes at the Eisenhower Medical Center in Rancho Mirage, said Kathleen Hall Jamieson, an Annenberg family spokeswoman who is director of the Annenberg Public Policy Center at the University of Pennsylvania.
In a statement released Thursday, former First Lady Nancy Reagan called Annenberg "a dear and longtime friend" and praised the couple's "unparalleled" philanthropy that "left an indelible print on education in the United States."
When Ronald Reagan appointed Annenberg to the protocol post in 1981, it was as if she had spent the first 63 years of her life preparing for a role in which attention to etiquette and diplomatic detail play such an important part.
What she called her only other "meaningful job" didn't come with a salary but took her to London, where Walter served as U.S. ambassador to Britain from 1969 to 1974. She had delighted in mingling with the royal family, entertaining and spending $1 million of Annenberg money refurbishing the ambassador's mansion.
Her husband, who once owned a communications empire that included TV Guide, was one of the country's most generous philanthropists, giving away more than $2 billion in cash in addition to a trove of art, according to "Legacy," an Annenberg biography by Christopher Ogden.
The Annenbergs gave about $290 million to USC, making the family the largest single donor in the school's history. They founded USC's Annenberg School for Communication in 1971 and the Annenberg Center for Communication, created to align and promote communications technologies, in 1993.
Ernest J. Wilson III, dean of the Annenberg School, said in a statement Thursday that "her remarkable philanthropy" and "engagement with the power of communication to improve humanity truly" have changed the world.
After her husband died in 2002, Leonore Annenberg became president of the Annenberg Foundation and continued giving millions away. More than $100 million was donated for an expansion of Eisenhower Medical Center and $10 million was given to the Reagan Presidential Library near Simi Valley for a center to teach children about civic responsibility and the U.S. presidency. In 2004, $25 million was given to build the Walter and Leonore Annenberg Center for Information Science and Technology at Caltech in Pasadena.
On the Annenberg Foundation website, Annenberg's stepdaughter, Wallis Annenberg, expressed "deep sadness" over Leonore's death and stressed that the organization's commitment to philanthropy will continue "for generations."
In the early 1950s, the Annenbergs began building a renowned collection of Impressionist and Post-Impressionist masterpieces that was worth an estimated $1 billion when they pledged it to the Metropolitan Museum of Art in 1991. The collection of about 50 works -- including paintings by Cezanne, Renoir, Monet and Van Gogh -- usually hung in their 32,000-square-foot mansion in Rancho Mirage.
Designed by Los Angeles modernist architect A. Quincy Jones, the airy home on the 240-acre estate was completed in 1966 for a reported $3 million. Annenberg was known for her attention to detail as decorator and hostess at the desert compound lushly planted to resemble an English country estate.
Known as Sunnylands, the estate that was their winter home had given refuge to President Nixon after his resignation over the Watergate scandal and was the site of Frank Sinatra's 1976 marriage to Barbara Marx. Actor Gregory Peck and entertainer Sammy Davis Jr. had been guests. But no one was allowed to just drop by.
"Even we absolutely must wait for an invitation," Diane Deshong, one of her two daughters, told the Washington Post in 1981.
With Annenberg's death, Sunnylands will be made available to the president of the United States and other high-level government officials to use as a diplomatic retreat. Eventually it also will be open for public tours three days a week, Jamieson said Thursday.
The Annenbergs also kept a chalet in Sun Valley, Idaho, and an estate outside Philadelphia.
When a Times reporter noted in 1981 that many people would be satisfied to stay by the pool instead of going to Washington to wrangle over diplomatic ceremony, Annenberg replied: "But what if you had done that for nine years . . . and suddenly you were offered a challenge?"
The $50,000-a-year job as protocol chief was the first paying position she had ever had. She was surprised that she adored it, Annenberg told The Times in 1981, and at 63 "was amazed to find out" she could do it.
In early 1981, she was put in charge of a staff of 40 in Washington, who didn't know what to expect from an international hostess who wore $3,000 suits and had a multimillion-dollar jewelry collection. Early on, Walter was overhead saying, "Remember, Motherrr, as we learned in London, it's the career people who saved our bacon and made the world go round."
"Word spread fast. Both Annenbergs seemed approachable, normal and nice," Ogden wrote in "Legacy," an unauthorized rags-to-riches biography of Walter Annenberg and his father.
As chief of protocol, Leonore held the rank of ambassador, with duties that included managing visits for heads of state and arranging presidential visits overseas. She also ran Blair House, a guest residence for visiting dignitaries. Since the house was in poor condition, she got her husband to help fund its refurbishment.
She endured one firestorm of controversy for curtsying to Prince Charles when he visited the U.S. in April 1981. Many people felt such a deferential dip by a State Department official to a member of the British royal family was inappropriate.
Annenberg chalked up the naturalness of the move to being a diplomat's wife in England, "where every single wife of every foreign ambassador curtsies to the royal family."
By December 1981, she had decided to resign to spend more time with her husband, whom she mainly saw on weekends at their baronial manor outside Philadelphia, where his publications empire had been based. In accepting her resignation, Reagan praised her "exceptional grace and wisdom," according to the biography.
Leonore Cohn was born Feb. 20, 1918, in New York City, to Max and Clara Cohn. When Lee -- as she was called -- was 7, her mother died, which caused her father to collapse. He ran a failing textile business.
She was raised in the exclusive Los Angeles neighborhood of Fremont Place by her uncle Harry Cohn, who founded Columbia Pictures. Cohn gave his brother a job making short subjects for the studio while Lee and her younger sister Judith attended Page boarding school for girls in Pasadena.
"My father gave us away. He just couldn't manage it," Annenberg was quoted as saying in "Legacy."
Harry's wife, Rose, raised her as a Christian Scientist, and that remained important in Annenberg's life. She also learned how to throw a society party by observing the post-performance buffets her aunt gave at the Hollywood Bowl.
Soon after graduating from Stanford University in 1940, Leonore married Beldon Katleman, whose family owned real estate and a national parking lot chain. The couple had a daughter, Diane, but divorced within a few years.
By 1946, Leonore had married the much older Lewis Rosenstiel, the multimillionaire founder of the Schenley liquor distillery, and they had a daughter, Elizabeth. He worked incessantly, and their marriage ended in divorce. She was lonely when she met Walter Annenberg in 1950 at a party in Boca Raton, Fla. Observers recalled that their chemistry was instant.
In 1988, Walter Annenberg sold his Triangle publishing company to Rupert Murdoch for $3 billion.
Her third marriage and husband were "fabulous," Annenberg often said.
"I admit that I have had a charmed life," she told the Washington Post in 1981. "It is true, and I am grateful for it."
In addition to her daughters, Diane Deshong of Beverly Hills and Elizabeth Kabler of New York, Annenberg is survived by her stepdaughter, Wallis Annenberg of Los Angeles; a sister; seven grandchildren; and seven great-grandchildren.
Plans for a memorial will be announced in coming months.
Instead of flowers, the family suggests that donors give to the charity of their choice.