Correction: An earlier version of this article incorrectly reported that Mrs. Lear retired from the stage after a 1985 performance at the Metropolitan Opera. She continued performing in operas and concerts for a number of years.

Evelyn Lear, an American soprano who became a preeminent interpreter of contemporary opera and enlivened the international stage with her commanding portrayal of characters she called “neurotic modern heroines,” died July 1 at Brooke Grove nursing center in Sandy Spring. She was 86.

Her son Jan Stewart confirmed her death but did not provide the medical cause. Mrs. Lear had settled in Rockville about two decades ago with her now-late husband, the acclaimed Wagnerian bass-baritone Thomas Stewart. For decades they performed together around the world.

Mrs. Lear built a repertoire that spanned centuries — from the classical purity of Mozart to the technical fireworks of 20th-century composers such as Alban Berg. Her signature role, and the one that catapulted her to fame in the early 1960s, was the title character of Berg’s “Lulu.”

Based on two plays by the late 19th and early 20th century German dramatist Frank Wedekind, “Lulu” tells the story of a reckless vamp ultimately killed by Jack the Ripper. Elisabeth Schwarzkopf, another celebrated soprano, once called Mrs. Lear’s portrayal of the femme fatale “one of the supreme achievements of the operatic stage anywhere in the world.”

Mrs. Lear had learned the punishingly difficult part in only a few weeks after agreeing to step in for another soprano at the Vienna Festival in 1960. She “nearly fainted,” she once said, when she for the first time saw the score’s wild melodic leaps.

Evelyn Lear is shown here performing with her husband, Thomas Stewart.(Photo by Ray Lustig/The Washington Post) (Ray Lustig/THE WASHINGTON POST)

At the time, Mrs. Lear and Stewart were singing principally in Germany, where both had traveled on Fulbright fellowships after floundering for years in the United States. Like many opera singers of their generation, they were overlooked at home as American opera houses pursued the glamor of European artists.

The Vienna Festival provided what Mrs. Lear called her “break.” At that concert performance of “Lulu,” under the baton of Karl Boehm, she stunned the notoriously exacting crowd. Two years later, she returned to Vienna for the Austrian stage premiere of Berg’s opera.

“The seeing was almost as important as the hearing, for she not only sang the in­cred­ibly difficult part with apparent ease, she looked the part of the temptress, she acted it, and she had a stage presence,” music critic Edward Downes wrote in the New York Times.

By all accounts, Mrs. Lear possessed the prized operatic combination of superior singing and acting abilities. She considered herself, in fact, a “singing actress.” When she tried out for trouser roles — the stage term for a male character played by a woman — she actually showed up for the audition in pants.

Traditionalists tend not to take well to the wild chromatics and atonality that characterizes much of modern opera. But Mrs. Lear sang such music so beautifully, Peter Russell, the general director of Vocal Arts DC, said in an interview, that she forced the skeptics to reconsider.

Patrons of the Kennedy Center, he added, would stay to hear Mrs. Lear perform in operas that otherwise might have sent them running and “screaming down Virginia Avenue.”

Mrs. Lear sang in many of the world’s great opera venues, including Milan’s La Scala, London’s Royal Opera House in Covent Garden and New York’s Metropolitan Opera House at Lincoln Center, where she made her debut as the scheming Lavinia Mannon at the 1967 world premiere of “Mourning Becomes Electra,” Marvin David Levy’s work based on a play by Eugene O’Neill. (When Stewart made his Met debut a year earlier, the New York Times marked his coup with the headline: “Mister Stewart Gets There First.”)

“Nowhere in Evelyn Lear’s realization of Lavinia Mannon is there a false step, no idle gesture, nor a word or note lost,” Washington Post music critic Paul Hume wrote of her performance. “She is a consummate artist who sings and acts with all the light and shade, the force or the caress needed to fulfill the musical and emotional demands of the famous role.”

Her success at the Met helped Mrs. Lear solidify her reputation in the world of modern opera. She sang leading roles in “Wozzeck,” also by Berg, and “Erwartung” by Arnold Schoenberg, the Austrian composer who revolutionized 20th-century classical music with his twelve-tone composition style.

Yet Mrs. Lear also excelled in 18th- and 19th-century music. Especially after a vocal crisis in the late 1960s, which left her unable to sing for a time, she pursued the relatively contained (although by no means easy) roles of traditional opera.

They included Cherubino in “Marriage of Figaro” and Donna Elvira in “Don Giovanni,” both by Mozart, and the title character in Puccini’s operas “Tosca” and “Manon Lescaut.” From the early 20th-century German repertoire, her roles included several parts from Richard Strauss’s “Der Rosenkavalier.”

Mrs. Lear gave a farewell performance at the Metropolitan Opera in 1985 but continued performing in operas and concerts for a number of years. She taught at the University of Maryland for about a decade and gave master classes around the world. She joined her husband in founding the Evelyn Lear and Thomas Stewart Emerging Singers Program in partnership with the Wagner Society of Washington. One of the program’s most prominent participants, Jay Hunter Morris, sang at the Met in “Siegfried” in 2011 and in “Götterdämmerung” in 2012.

Mrs. Lear’s recordings with the classical label Deutsche Grammophon, particularly the Berg operas, are considered classics. The recording of “Wozzeck,” featuring Mrs. Lear as Marie, won the Grammy Award for best opera in 1965.

Evelyn Shulman was born Jan, 8, 1926, in Brooklyn. Her father, a Siberian immigrant, became a lawyer, and her mother was a professional classical singer. Her maternal grandfather was a Jewish cantor. As a girl, Mrs. Lear studied the piano and played the French horn with a Tanglewood student orchestra conducted by a young Leonard Bernstein.

When she was about 18, she married Walter Lear, a physician, and moved to Arlington. Her nonprofessional opera debut took place at the Agriculture Department, where she sang in Kurt Weill’s “Down in the Valley,” an American folk opera with libretto by Arnold Sundgaard.

After she and her first husband divorced, Mrs. Lear returned to New York in the 1950s and began studying at Juilliard, where she met Stewart while working on a duet from “Porgy and Bess.”

Stewart died in 2006 after 51 years of marriage. Survivors include two children from her first marriage, whom Stewart legally adopted, Jan Stewart of Arlington and Bonni Stewart of Mississauga, Ontario; and two grandchildren.

“Lulu” seemed to retain a special place in Mrs. Lear’s memory. Asked why she agreed to take on the opera in Vienna on such short notice, she once told an interviewer: “The American never says no!”