Astrid Varnay, who died Monday in Munich at 88, was one of the greatest dramatic sopranos of the 20th century, and a leading singer at the Metropolitan Opera and at the Bayreuth Festival during the glory years of the 1950s and early 1960s.

Known as for the tonal richness of her large voice, which she wielded with passionate intensity, she was also an accomplished actress. This endeared her to Wieland Wagner, grandson of the composer, whose abstract stagings at Bayreuth riled traditionalists by doing away with props. Wieland countered his critics thus:: “Why do I need a tree on stage when I have Astrid Varnay?”

Her performance debut at the Met, the day before Pearl Harbor, 1941, could hardly have been more dramatic, as she stepped into the role of Sieglinde in Wagner’s “Die Walküre” in a nationally-broadcast performance conducted by Erich Leinsdorf. Irving Kolodin, longtime music critic of the New York Sun and historian of the Met, called Varnay’s debut “the most improbable and, considering its outcome, the most remarkable in the history of the Metropolitan.” Having begun as the “fifth cover” — four other replacements were unavailable — Varnay went on to give 200 performances at the Metropolitan, many of them in Wagner roles.

But for many Wagnerians the summit of her career was reached in Bayreuth after the Festspielhaus reopened in 1951. Wieland Wagner’s productions, now regarded as among the most powerful and influential of the 20th century, included a core group of singing actors that included, besides Varnay, such eminent Wagnerians as Wolfgang Windgassen, Hans Hotter, and Josef Greindl. Among them also was Martha Mödl, beloved colleague of Varnay’s, with whom she alternated as Brünnhilde in the “Ring” operas, and as Isolde. Varnay was the first American soprano to sing all three Brünnhilde roles at Bayreuth. Recordings of Varnay’s Bayreuth performances have circulated widely.

Because Varnay’s Met career largely pre-dated that of another great Swedish Wagner soprano, Birgit Nilsson, opera-goers in America, are likely to think of Varnay as senior to Nilsson. Yet they were actually born in the same year, 1918, Nilsson on a farm in southern Sweden, Varnay in Stockholm, of Hungarian parents, both of whom were associated with the Royal Opera. Her father, Alexander Varnay, was a tenor and stage director and her mother, Maria Javor Varnay, a coloratura soprano. When Astrid was a toddler, the family went abroad in search of opportunities, first to South America, later to New York, where her father died in 1924 at 35. Her mother decided that they would stay in the New York area, and Astrid was reared as an American.

Her first voice teacher was her mother. Later she studied voice with Hermann Weigert, a member of the Met’s music staff. After a year and a half with Weigert, whom she married in 1944, she auditioned for the Met and was given a contract. Varnay has said her idol, “as far as voice was concerned,” was Kirsten Flagstad, another great Scandinavian soprano.

Other roles at the Met quickly followed her December 6, 1941, debut. Six days later she replaced Helen Traubel, to sing Brünnhilde, in her debut opera of “Die Walküre.” By within a month she sang Elsa in “Lohengrin” and Elisabeth in “Tannhäuser.” By the 1950-51 season she had sung all the 14 principal soprano parts in the Wagner operas except Brünnhilde in “Götterdämmerung.” In addition to her Wagnerian roles, she sang Italian opera at the Met, having first sung in “Aida,” “La Gioconda” and “Otello” in Mexico City in 1948. She even sang in an American opera, Gian-Carlo Menotti’s “The Island God,” which she sang in its world premiere, which also occurred during her busy debut season. She was acclaimed for her performances as Strauss’s Elektra and Salome. When she sang Isolde at Covent Garden in 1948, Ernest Newman, the English critic and Wagner biographer, called her performance “one of the finest sung and best acted Isoldes.”

Varnay left the Met in 1956 after a series of conflicts with the opera’s General Manager, Rudolf Bing. In her 2000 memoir “Fifty-Five Years in Five Acts,” Warnay wrote, “Mr. Bing, who had certainly not cornered the market on the milk of human kindness, seemed to regard much of the German repertoire, particularly the operas of Richard Wagner and the people who sang them, as not worthy of the attention he accorded other areas of the theater’s activities.” When Bing asked that he be informed about future engagements, she replied, “You will be able to read about them in the papers.”

She sang mainly in Munich and with other German companies, finally returning to the Metropolitan in 1974 to sing Kostelnicka in the Met’s premiere production of Janacek’s “Jenufa.” Later she appeared in another Metropolitan Opera premiere, that of Kurt Weill’s “The Rise and Fall of the City of Mahagonny,” taking the role of Leocadia Begbick. Her last Met performance was on December 22, 1979 but she continued to sing in Munich until 1995.

Astrid Varnay

Born April 25, 1918, in Stockholm, Sweden; died September 4 in Munich of a pericardial infection; there are no immediate survivors.

Mr. Loomis writes about classical music and opera for The New York Sun.