COLORBLINDNESS on the opera stage is a fact of life, yet it never hurts for a singer to look the part, as the bass Kwangchul Youn recognizes. "It takes courage to cast a short Korean in parts where people expect a tall, blond European," Mr. Youn said with a broad smile in 2008, after singing the betrayed King Marke in Wagner's "Tristan und Isolde" at the Metropolitan Opera for the first time. Mr. Youn stands a little over 5-foot-7 (1-meter-71, he says, not yielding a centimeter).
At the season premiere a week before, René Pape — a tall European, though not blond, and a fixture in the Met's "Tristan" since 1999 — had steeped the king's laments in a wintry isolation. Mr. Youn struck a chord of autumnal romance, resonant with compassion and abiding love.
For many, Mr. Pape has long been the gold standard in this music, but ranking such thoroughly realized, deeply personal interpretations is not really meaningful. When the conductor Daniel Barenboim, who has worked with both artists for years, pushed Mr. Youn forward for a solo bow, the Met audience gave him a hero's welcome. At last, it seemed, New York fans had taken his true measure.
His company debut in 2004, as the high priest Sarastro in Mozart's "Zauberflöte," was largely overshadowed by Julie Taymor's new production. (One critic likened Mr. Youn to a Chinese emperor, another to a Mikado statue, and musical evaluations were mostly limited to single, appreciative adjectives.) By now Mr. Youn has appeared here 50 times, mainly in supporting roles as dignified authority figures. Last season he cut loose as Ferrando, a superstitious captain of the guard with a long memory for dark doings, in David McVicar's new production of Verdi's "Trovatore." On Thursday, Mr. Youn, 45, returns as the heroine's compassionate but double-dealing spiritual adviser, Raimondo, in a revival of Donizetti's "Lucia di Lammermoor" starring Natalie Dessay.
That Mr. Youn's New York breakthrough took place under Mr. Barenboim's aegis seems poetic justice. Their relationship goes back to 1993, when Mr. Youn auditioned at the Staatsoper Unter den Linden in Berlin, where Mr. Barenboim was just beginning his tenure as music director.
By his own account, Mr. Youn was still very green when he joined the Staatsoper. Mr. Barenboim does not disagree.
"He had a beautiful voice and great musical sensitivity but not anywhere near the kind of musical knowledge he has now," Mr. Barenboim said recently from Berlin. "His progress was very gradual, very evolutionary. At first he was very stiff onstage. In the meantime he has become a wonderful singer, musician and actor."
And did his height ever stand in his way? "Never," Mr. Barenboim said. "Remember Edward G. Robinson? There you are. He was also very small but with an aura of great authority."
Even so, the Satanic Méphistophélès, in Gounod's "Faust," might seem a stretch for a man of Mr. Youn's build. Yet he triumphed in the part at the Vienna State Opera in 2008, and the sulfur and zest of his portrayal shine through in a crackling live recording from Orfeo.
"Who knows how big the Devil is?" Mr. Youn said late last year from Seoul. "So I make him small and sly, like a snake, using a big voice to contrast with my small person. And I play him big, avoiding any small gestures."
Mr. Youn was born outside the provincial capital of Chungju in South Korea. His parents grew rice then; now they grow apples. "My village was very poor," he said in German. "There was no electricity. We read by lantern light. In school I learned the names Bach, Mozart and Beethoven but heard nothing of their music."
He liked to sing, and when his voice broke, he developed a dark, burly sound of unusual richness. He studied in Chungju, intending to become a voice teacher. In 1990 he discovered recordings of the great Bulgarian bass Boris Christoff, which opened a whole new world.
"Christoff sang not only with his voice," Mr. Youn said, "but with language, with his mentality. There wasn't anyone like that in Korea."
Perestroika had dawned, and study in the Eastern bloc was affordable and easy to arrange. In honor of his idol, Mr. Youn headed for Bulgaria.
"My thought was just to get an idea of the style and then to go home," he said. "But Professor Lesa Koleva in Sofia sent me on to Germany." While still enrolled at the University of the Arts in Berlin, Mr. Youn lucked into Plácido Domingo's first international vocal competition, in Paris, as an alternate, and shared top honors with the sopranos Ainhoa Arteta, Inva Mula and Nina Stemme.
From 1994 to 2004, Mr. Youn took home a regular paycheck as a member of the Staatsoper ensemble. Then he went freelance, repatriating with his wife and twin daughters in Seoul, where he teaches between singing engagements around the world.
"Berlin laid the foundation for my international career," Mr. Youn said. "I was really ready to learn, to see what the great basses do onstage." Basses like Fritz Hübner and Siegfried Vogel, many years his senior, as well as Mr. Pape, who is only a year older but blossomed much sooner.
"It was hard," Mr. Youn said. "I'm a foreigner in European culture. So I went to lots of movies to study Western gestures. That was harder for me than the singing. Besides, basses often play old men, so I had to learn to hide my youth."
Studying new roles, he went religiously to primary sources, even beyond the score: Shakespeare for Verdi's "Macbeth," Goethe for "Faust," Schiller for "Don Carlo."
Judging from appearances, you might peg Mr. Youn as a comic bass, made to order for fuddy-duddies, blusterers, put-upon servants and elderly dupes. But the repertory for his voice type also includes a gallery of gods, kings and demons, to borrow the title of a recital album by Mr. Pape.
By now Mr. Youn has staked out these grandest and most coveted parts too. At the Bayreuth Festival in Germany, the shrine to Wagner, he has won accolades several years running as Gurnemanz, the grizzled knight of the Holy Grail in "Parsifal." Now it is his international calling card.
Another potential signature role is King Philip in "Don Carlo," which Mr. Youn first sang in Frankfurt, in 2007 and is contracted to sing in Vienna next year. Ten days before the Frankfurt premiere, the Korean tenor Yonghoon Lee unexpectedly joined the cast as Don Carlo, the king's son and a perpetual thorn in his side, causing something of a flurry.
Not that Mr. Youn and Mr. Lee are the only Koreans working in Western opera houses. At the Met, the elegant Hei-Kyung Hong has been a regular in Mozart, Verdi and Puccini since her debut in 1984. This season, the intrepid coloratura Kathleen Kim is on the roster there for high-wire acts in John Adams's "Nixon in China" and in Richard Strauss's "Ariadne auf Naxos." Still, the pairing of two Koreans in Frankfurt struck an exotic note the German press could not resist.
"The magazines wrote that we really looked like father and son," Mr. Lee said recently at the Met, where he made his debut this season in "Don Carlo." But what counted more for Mr. Lee was the intensity of their interaction as artists.
"Onstage we're not Koreans," he said. "I'm not Yonghoon, and he's not Kwangchul. We're the characters. And when Kwangchul sings a phrase, I feel as if I'd never heard it before. It was hard not to hate him."
As Mr. McVicar, who directed the Frankfurt "Don Carlo," reported in a recent e-mail, Mr. Youn's characterization stuck close to Schiller, revealing not "a dignified older man" but a person "tormented, middle-aged, sexually active."
"I think Youn is a very sexy, charismatic, dynamic performer," Mr. McVicar added. "And I personally feel that his recorded Don Giovanni is one of the most impressive in the catalog."
For the sheer richness, roundness and bounce of the red-blooded bass sound, for the variety of expression from menace to silken seduction and sheer high spirits, for the pointed clarity of the text, Mr. Youn's rendition of Mozart's blasphemous rake is indeed of a high order, conjuring in the mind's eye a personage and a personality of spellbinding vitality. But the recording, on Arte Nova, was a studio production pure and simple, without any theatrical component.
"I'm not as tall as most of my colleagues," Mr. Youn said. "Some directors want you to be two meters. But I have my own interpretations, and people are getting used to me."
Two meters? That's nearly 6-foot-7. Even allowing for poetic license, Mr. Youn is not holding his breath for further offers of that particular role.
"I've yet to find a director who can picture me as Don Giovanni," Mr. Youn said.
But why not? After all, he has sung Fasolt, the amorous giant in Wagner's "Ring des Nibelungen," both in Bayreuth and at the Teatro Alla Scala, in Milan. As the director Guy Cassiers showed with a canny use of looming shadows at La Scala, a little imagination can work wonders.