Dina Merrill in 1962. (Harold P. Matosian/AP)

Dina Merrill, an actress whose aristocratic poise and willowy good looks earned her many film and TV roles as well-bred society women — parts that reflected her own life as a scion of two of America’s richest families — died May 22 at her home in East Hampton, N.Y. She was 93.

The cause was Lewy body dementia, said her husband, Ted Hartley.

Long after her acting career peaked, Ms. Merrill remained a steadfast presence on the New York social scene. She spent decades as a philanthropist and fundraiser for charities, and she was often described as an exemplar of chic fashion and elegance.

Her parents were Edward F. Hutton, co-founder of the stock brokerage, and breakfast foods heiress Marjorie Merriweather Post, who married into additional fortunes and became a dominant Washington socialite of her era. The oft-chronicled Woolworth scion Barbara Hutton was a cousin.

From a young age, Ms. Merrill was determined to pursue acting despite skepticism from her parents and others. She said her father called her a “fool.” Studio executives and entertainment journalists chalked up her ambition to a lark, asking why she didn’t buy a studio instead of bothering with casting tryouts. She was dubbed the “Social Register Cinderella” during a Hollywood publicity buildup in the late 1950s.

Actress Dina Merrill, RKO Chairman Ted Hartley and actress Stockard Channing in 2005. (Stephen Shugerman)

By critical assessment, Ms. Merrill was an athletic, ice-blond goddess with refined features and impeccably sculptured hair but an otherwise colorless presence in movies. She bore a skin-deep resemblance to Grace Kelly but, unlike that Oscar-winning actress who retired from acting in 1956 to marry the prince of Monaco, Ms. Merrill never smoldered with passion or conveyed wrenching emotional vulnerability.

After some TV work, her Hollywood breakthrough came in 1957 as a library reference clerk in “Desk Set,” a comedy that marked the eighth screen pairing of Katharine Hepburn and Spencer Tracy. She said the screen veterans were “so generous and so nice and kind” to her — and stood in contrast to Marlon Brando, who reportedly vetoed her as a co-star that same year in the drama “Sayonara” because she was “too tall and . . . too damn bossy.”

Instead, she played a Navy intelligence officer opposite Jerry Lewis in the farce “Don’t Give Up the Ship” (1959) and a shipshape nurse in “Operation Petticoat” (1959), a wartime comedy with Cary Grant and Tony Curtis.

In director Fred Zinnemann’s “The Sundowners” (1960), Ms. Merrill played a city woman who marries a ranch owner and suffers from extreme loneliness in the Australian outback. Although a small role, it afforded her a rare chance at an excellent picture, which starred Robert Mitchum and Deborah Kerr.

In “BUtterfield 8” (1960), a drama that won Elizabeth Taylor an Oscar for best actress for portraying a doomed party girl, Ms. Merrill had a thankless part as the long-suffering society wife of Laurence Harvey.

From there, it was back to largely forgettable comedies and dramas: an unsympathetic spouse of a crusading assistant district attorney (Burt Lancaster) in “The Young Savages” (1961); a snobby sophisticate who dates widower Glenn Ford in “The Courtship of Eddie’s Father” (1963); and an interior designer in the innuendo-laced Bob Hope farce “I’ll Take Sweden” (1965).

In addition to guest appearances on TV well into the 1990s, Ms. Merrill periodically returned to film work. In supporting roles, she joined the crew of family eccentrics in Robert Altman’s social satire “A Wedding” (1978) and played a snooty, white-gloved matron in “Caddyshack II” (1988), a golf comedy starring Jackie Mason.

Dina Merrill and her then-husband, actor Cliff Robertson, in 1966. (Charles Del Vecchio/The Washington Post)

Nedenia Marjorie Hutton was born in New York on Dec. 29, 1923, and grew up amid more than plenty. Her family’s Manhattan apartment had 66 rooms, and their retreat on the North Shore of Long Island had 59, in addition to a pool, tennis courts and a horse show ring. Their sprawling South Florida showplace, Mar-a-Lago, was purchased in 1985 by businessman and future president Donald Trump, who converted it into a private club.

The Huttons entertained on a lavish scale, sometimes hiring the cast of Broadway shows and members of the Ringling Bros. and Barnum & Bailey Circus to perform privately for family and guests. But amid splendor, the Hutton-Post marriage was in distress, with Marjorie convinced that her husband was philandering with a maid. They divorced.

Meanwhile, Dina, as she became known, graduated in 1941 from Washington’s Mount Vernon Seminary, where she excelled at field hockey and served as president of the dramatic club. Both activities went against her mother’s wishes, the first because she felt it was unladylike to sweat, the second because it signaled career aspirations other than marriage and motherhood.

Dina attended the American Academy of Dramatic Arts in New York, toiled in summer stock productions and, having adopted the stage name of Merrill, landed a small role on Broadway in John Van Druten’s short-lived comedy “The Mermaids Singing” (1945).

The next year, she married Stanley M. Rumbough Jr., an industrialist and heir to the Colgate-Palmolive fortune. She did some modeling while raising their three children but harbored unfulfilled acting desires that eventually caused the marriage to rupture.

“Stan wanted me to be a housewife and mother,” she later told People magazine. “But after eight years I had gotten antsy. Men think we can’t do two things at once. They can’t, but we can. Women are more resilient.”

In 1966, she wed actor Cliff Robertson, who won an Academy Award for his leading performance in “Charly” (1968). Ms. Merrill’s private wealth, including well over $50 million inherited from her parents, allowed her the freedom to go months and years without work and survive scathing reviews for her Broadway appearances in the melodrama “Angel Street” (a 1975 revival) and the musical “On Your Toes” (a 1983 staging of the old Richard Rodgers-Lorenz Hart show).

Her financial independence also made her more willing to single out wrongdoing by powerful people in the tightknit film capital.

The boss of Columbia Pictures, David Begelman, had been forging Robertson’s names on checks as part of an embezzlement scheme. But Begelman was well-liked and many were grateful to him for having brought the financially ailing studio to profitability. At Ms. Merrill’s urging, Robertson took his charges public, leading to Begelman’s temporary downfall but also the actor’s own unofficial blacklisting in movies for years to come.

After she and Robertson divorced, she married actor-turned-businessman Hartley in 1989. They acquired a majority stake in what was left of the old Hollywood movie studio RKO Pictures, working mostly in production and distribution for the next decades.

Besides her husband, of East Hampton, N.Y., survivors include two children from her first marriage, Stanley Rumbough III of Palm Beach, Fla. and Nedenia “Nina” Rumbough Roosenburg of Brays Island, S.C.; a stepson, Philippe Hartley of La Canada, Calif.; 10 grandchildren; and two great-grandchildren. A son from her first marriage, David, died at 23 in a boating accident in 1973. Her daughter with Robertson, actress, writer and producer Heather Robertson, died in 2007 of ovarian cancer.

Ms. Merrill sat for years on the board of her father’s Wall Street investment firm. She also helped raise money for the Juvenile Diabetes Foundation (son David was diabetic) and the New York City Mission Society, which helps disadvantaged youths. She also was a trustee of the Kennedy Center for the Performing Arts in Washington, and she helped lead an abortion rights coalition within the Republican Party.

Reflecting on her heritage, she told the Associated Press in 1988: “I was very fortunate that I did have everything I wanted handed to me on a silver platter, so to speak. But I also had good training from both parents about the work ethic, about the fact that I was lucky, as they were. And that a lot of that had to be put back into the world, to help other people get a start and to be fortunate, too, in their way.”