HOLLYWOOD, Calif., June 18--Ethel Barrymore, last of the trio known to Broadway and Hollywood as "The Royal Family" of acting, died here today of a heart ailment. She would have been 80 years old on Aug. 15.

Miss Barrymore started on the stage at 14 and made her last public appearance on television during a testimonial to her on her seventy-eighth birthday. The two others in the Barrymore triumvirate were her brothers, John, who died in 1942, and Lionel, who died in 1954.

Although Miss Barrymore talked amusingly of the past, she refused to live in it and had little patience for those who resented changes in drama brought on by movies and television. In one of her last interviews, several weeks ago, she said:

"We must recognize that change is not going to appeal to us personally if we are irrevocably determined to abide by the traditional standards of taste."

The square-jawed actress with the classical profile had done no acting for movies since 1954, when she made "Young At Heart," with Frank Sinatra and Doris Day. She took her final acting role on television in a "Playhouse 90" dramatization in 1956.

While no longer active as a performer, Miss Barrymore maintained a strong interest in the theatre, movies and television. Leading stars of Broadway and Hollywood would visit or telephone her about show business.

With Miss Barrymore at her death in her modest apartment in Beverly Hills were her son, Samuel Colt, who lived with her, and her nurse and companion, Anna Albert. Her daughter, Mrs. Ethel Miglietti, and her other son, John Drew Colt, were said to be flying here. No date has been set for the funeral.

More Regal Than Royalty

Born to the theatrical purple, but by her own right and dramatic genius holder of the stage's brightest scepter, Ethel Barrymore once received this crowning accollade: "More regal than royalty."

The star, descended from two of the theatre's great families--the Barrymores and the Drews-- achieved her dramatic fame in the golden era of the American theatre and held her grip on the hearts of theatregoers long after she had moved from glamorous roles to mature characterizations.

Critics have written of weeping from the beginning to the end of a play Miss Barrymore acted and forgetting completely to follow the plot. Clifford Odets has told the story of trying to select a pathetic little hat for her to wear in her role as the poor London charwoman in the movie "None But the Lonely Heart." After trying on countless hats, Miss Barrymore turned for approval of the latest headgear and Mr. Odets burst into laughter.

"You still look like a queen," he told her.

She was then 65 years old and Hollywood passed over the glittering array of fine talent that year to give its own Academy Award for acting to Broadway's still-reigning sovereign.

Held Audiences Enthralled

Miss Barrymore was described by Harold Clurman, author and critic, as possessing a naturally regal quality that was as easy and organic for her as breathing.

"It is a spiritual rather than a social quality," he observed. "Very few kings and queens have possessed it."

Her acting held her audiences enthralled and silent. And so did her manner. She was asked once what she did when playgoers began coughing in the theatre. "I never let them cough," she replied, then added: "They don't dare!"

Throaty and vibrant, her voice captivated audiences through half a century and more. But, as one admirer noted, it did not merely make a rich sound--it was the echo of an inexhaustible wealth of experience. It was the echo of a life Miss Barrymore once thought of describing as "Too Many Tears" in her biography, but later decided to call "Memories" because of her reticence about the expression of her private emotions.

Hailed by Truman

The actress, who had a threatre named after her--on Forty-seventh Street, west of Broadway--and who on her seventieth birthday was hailed by former President Harry S. Truman as "a great lady and a great artist," recalled once that she had never really wanted to be an actress.

"I always hoped to be a pianist," she confided. "But I had to eat, and acting seemed like the natural thing to do, since the family was already in it." Long after she had achieved fame she said she was "always scared to death" because of her shyness when she went on stage.

Last night at 8:30 in remembrance of Miss Barrymore, the marquee lights of the Ethel Barrymore Theatre were dimmed for ten minutes, just before the performance of "A Raisin in the Sun."

Miss Barrymore, who was born in Philadelphia on Aug. 15, 1879, was 14 when she decided it was time to think about earning a living. She left the Convent of the Sacred Heart in Philadelphia to join her grandmother, Mrs. John Drew Sr., one of the first of the outstanding American actresses. Miss Barrymore made her debut in New York in the role of Julia in "The Rivals," at the now defunct Empire Theatre on Jan. 25, 1894.

Elite of the Theatre

She was watched, carefully, by the critics. Her father was Maurice Barrymore, a matinee idol and a Beau Brummel of his day, and her mother was the lovely Georgiana Drew, whose family for generations had been among the elite of the theatre. Her mother's brother was John Drew and her great-grandmother, Eliza Lane, was an English actress and singer of note. These were her antecedents, and the critics were curious.

It was not a particularly brilliant debut, and managers did not rush to add this latest Barrymore to their lists of stars. But John Drew, whose leading lady then was the celebrated Maude Adams, found a small part for her in his vehicle "The Bauble Shop," and Charles Frohman, the producer, saw her and though she might do.

She was on her way. A few years, first, of small parts, tours and little cash. But she began to attract favorable attention and, in 1901, rose to stardom when Mr. Frohman gave her the leading role of Mme. Trentoni in "Captain Jinks of the Horse Marines."

Played in Noted Hits

Then, for a decade or more, she appeared in some of the hits of the day, including "Cousin Kate," "Sunday," "A Doll's House," "Alice Sit-by-the-Fire" and "The Silver Box." It was for "Sunday" that Miss Barrymore came out on stage to quiet the thunderous applause and announced: "That's all there is, there isn't any more"--a line that became a part of the national language.

Among her notable roles were in the plays "The Corn Is Green," "The Constant Wife," "School for Scandal" and "The Kingdom of God." She also appeared on the screen with her brothers in "Rasputin and the Empress."

It was in the early Ninetten Hundreds that Miss Barrymore became the idol of her public. Just as schoolgirls of later periods copied the late Jean Harlow's platinum-blonde hair, Joan Crawford's eyebrows and Hedy Lamarr's coiffure, young girls of Miss Barrymore's earlier days solemnly adopted what they called the "Ethel Barrymore voice," "Ethel Barrymore walk" and a dozen other mannerisms of the star.

Rumors of Marriage

On March 14, 1909, after it had been rumored at various times that she was to be married to a dozen or more men--among them Prince Ranjitsinihi, famous British-Indian cricket player; Gerald du Maurier, Capt. Harry Graham of the Scots Guards, and others--Miss Barrymore surprised her public with her marriage to Russell G. Colt, son of Col. Samuel Pomeroy Colt, then board chairman of the United States Rubber Company.

Three children, Samuel Colt, John Drew Colt and Ethel Barrymore Colt, all of whom have since made efforts toward theatrical careers, were born to them. In 1923, after numerous separations and reconciliations, Mr. Colt and Miss Barrymore finally were divorced.

About the time the motion pictures began raiding Broadway for stars, Miss Barrymore accepted a year's contract in Hollywood. Of her career in the silent films, Miss Barrymore once said that the only picture she ever made that she could bear to look at was "The Awakening of Helena Ritchie." She was very happy to return from the silents to the stage.

'Retired' in 1936

In 1936 she announced that she was "definitely" retired from the stage and intended to devote the rest of her life to the business of being a mother to her children. But a year later she was back on Broadway in the Theatre Guild's "The Ghost of Yankee Doodle." In 1938 she starred in the role of a 101-year-old matriarch in Mazo de la Roche's "Whiteoaks." In "Constant Wife" she gave a long run of 295 performances on Broadway, but later "The Corn Is Green" ran for more than a year in the initial showing.

Miss Barrymore never kept a single clipping and never collected a scrapbook. "I remember only what I want to remember," she declared. "Why clutter up the house with a lot of dead history?" She collected books, however, and devoured them. At one time, they lined the walls of her house, spilled over onto chairs, extra tables and the floor. Even her garage was lined with bookshelves--all packed.

Miss Barrymore could be very blunt. In 1933 she told an audience of Philadelphia clubwomen that they were "moronic" and that she did not know why she bothered to speak to them at all. On her seventy-fifth birthday she was asked what she thought of television. Her reply: "It's hell."