Correction: An earlier version of this article incorrectly referred to Mr. Fischer-Dieskau’s achievement as a recording artist. He was among the most prolific classical recording artists but was not featured on more recordings than any other artist.

Dietrich Fischer-Dieskau, the German baritone whose name is virtually synonymous with the German art song for several generations of postwar music lovers, died May 18 at his home in Starnberg, Germany. He was 86.

His death was confirmed by his fourth wife, the soprano Julia Varady. The cause of death was not disclosed.

Mr. Fischer-Dieskau was one of the great musicians of the 20th century. He pursued excellence with a single-minded intensity that led to such epithets as “the thinking man’s baritone,” and he documented the results on more than 1,000 LP’s, according to the Christian Science Monitor.

This prolific activity meant that for many listeners, Mr. Fischer-Dieskau became the veritable voice of German music. He used that voice — light and clear and wide-ranging — like an instrument to achieve myriad subtle shades of tone and color along with crisply enunciated texts.

He returned again and again to the core of his repertory, particularly where German art songs, or lieder, were concerned. He sang them, wrote books about them and recorded them as many as — in the case of Schubert’s magisterial song cycle “Winterreise” — eight times.

German baritone and conductor Dietrich Fischer-Dieskau, circa 1970. (Erich Auerbach/GETTY IMAGES)

Although lieder were Mr. Fischer-Dieskau’s calling card for many music lovers, the range and breadth of his musical interests was impressive. He was as well known for opera as for song. He never sang at the Metropolitan Opera, but he was a fixture on German opera stages from the very beginning of his career.

He sang everything from Verdi (the title role of “Rigoletto”) to Wagner (Wolfram in “Tannhäuser,” Amfortas in “Parsifal”) to contemporary composers who wrote for him, including Benjamin Britten (“War Requiem”) and Aribert Reimann (“Lear”).

Mr. Fischer-Dieskau aburptly retired from singing in 1992 after a performance of Verdi’s “Falstaff.” Singing “All the world’s a joke,” he realized that this was the perfect note on which to exit, and he canceled all future engagements the next morning. He continued his life in music as a writer, conductor and teacher, and he brought the same exacting standards to young singers that he brought to his own singing.

Tall and handsome, with big features that worked well on the stage, Mr. Fischer-Dieskau projected a certain dry reserve. Although he sang as if discovering each song for the first time, his supreme control struck some as too controlling.

He could sing with warmth, but he didn’t always seem to be a warm person. His unsparing directness could come across as arrogance.

“I achieved too much,” he told the British journalist Norman Lebrecht, matter-of-factly, during an interview in 2007. “I left too little for my successors.”

Albert Dietrich Fischer-Dieskau was born in Berlin on May 28, 1925, the third son of Albert Dietrich Fischer, a classicist and teacher. His mother, Theodora Klingelhöffer, loved the piano and was a formative influence in his life. (In 1934, his father added the “Dieskau” to the family name in a salute to forebears on the maternal side.)

Mr. Fischer-Dieskau was 12 when his father died. After the Nazis came to power, his older brother Martin, physically and mentally disabled, was removed to an institution, where he died.

After one semester at Berlin’s leading conservatory, Mr. Fischer-Dieskau was drafted into the German army and sent to the Russian front to care for horses in the cavalry. He ultimately ended up as a prisoner of war in Italy, where his fine voice was soon discovered and he was used to entertain the troops — so successfully that he was one of the last prisoners returned to his homeland.

The young singer resumed his conservatory studies, primarily with Hermann Weissenborn, who remained a mentor and guide until his death in 1959. He didn’t study long, though. He began gathering professional experience almost immediately. By 1948, he had made some radio recordings for an American radio station in Berlin, including Schubert’s “Winterreise.”

The head of the Berlin State Opera heard the recordings, invited the young singer to audition, and gave him the role of Posa in a new production of Verdi’s “Don Carlo.” Mr. Fischer-Dieskau quickly became a fixture in leading roles at the opera house. His many appearances in Verdi roles prompted the conductor Ferenc Fricsay to exclaim, “I never dreamed I would find an Italian baritone in Berlin!”

Then came the stations of a triumphant opera career: the Vienna State Opera, the Bavarian State Opera, the festival at Bayreuth (starting in 1954), and the title role in Mozart’s “Don Giovanni” at the opening of West Berlin’s new opera house in 1961.

Thereafter, he simply went from strength to strength, with all the accolades that attend the pinnacle of musical success: five Grammys, nearly 20 awards of the French Grand Prix du Disque, an unparalleled recording catalogue (“twice as many records as Placido Domingo,” the Christian Science Monitor pointed out) and awards for distinguished service from his country.

Mr. Fischer-Dieskau’s first wife, the cellist Ingrid Poppen, died of complications after the birth of their third son, Manuel, in 1963. (Manuel and two other sons from the marriage to Poppen, Matthias and Martin Fischer-Dieskau, survive him.)

Mr. Fischer-Dieskau was twice married and twice divorced before he married his student, Varady, in 1977. She brought a similar aura of authority to her performances, becoming something of a cult figure in German opera circles.

Standing at the peak of musical achievement, Mr. Fischer-Dieskau inevitably came in for his share of criticism. Some found him too cool, too dry or too calculated. But even those who were not personally touched by him could not fail to appreciate the scale of his achievement or his total commitment to his art.

“The thing that will always occupy me the most is music,” he said in an interview in 1995 in the magazine Opernwelt. “I have never been able to live without it, and in old age, you shouldn’t abandon that which is most important to you. That would surely have fatal consequences.”