By Richard Dyer

Karita Mattila was an original from the beginning, and everyone knew it, including her. She didn’t look like anyone else in opera and didn’t sound like anyone else either.

But she was more than a dozen years into a successful international career before people stopped describing her as “promising.” And until then, probably no one, not even the soprano herself, could have imagined the kind of singer and stage animal she would make of herself—for the cool blonde chrysalis has emerged the most electrifying singing actress of our day, the kind of performer who renews an aging art form and drives the public into frenzies. Even people who “don’t like” opera can’t help responding to her.

Mattila can radiate glamour like Dietrich, embody the passions of a peasant or an aristocrat, or pull on an electric pink bustier and opera-length glitter gloves and deliver “Diamonds Are a Girl’s Best Friend.’’ She can be the merriest widow who ever wore feathers in her hair and a black dress slit up above the knee, the better to waltz. Or she can embody a wife courageous enough to pass herself off as a man in order to rescue her husband from a political prison.

At nearly six feet tall, with platinum blonde hair, and at 44, a very buff 44, Mattila doesn’t exactly look like a Judean Lolita, but she recently enjoyed the greatest triumph of her career to date singing the title role in Strauss’s Salome in Paris and New York. At the Met, she executed a split during the Dance of the Seven Veils and briefly appeared fully nude, both duly slavered over in the press; one review pointed out that if the soprano ever gets tired of singing, she could make a career as a stripper. The radio public, away from all of this, could hear that she sang the role with shimmering, silvery, moonstruck tone that not so innocently carried an erotic charge.

A role like Salome shows how far opera has carried Mattila from her conservative religious upbringing on a farm in Finland, where she grew up living with no hot water. Even then, she was laying the groundwork for the future both when she knew it, and when she didn’t. The origins of her believable Fidelio probably lie in growing up surrounded by three brothers; she knows how young men behave. She started learning foreign languages as a schoolgirl, and today sings and acts with conviction in at least seven of them, as well as Finnish.

When she was 9, her parents thought learning to play the piano would be a good hobby; practice time might keep her away from boys. By the time she was 14, she had caught on to their game and she was ready to quit, but her parents encouraged, cajoled, and even bribed her to continue. Within a couple of years, she had fallen in love with music and begun to study singing on the side. She says her aunts tell her that she had “such a husky voice—but very loud.’’

She attended the Sibelius Academy in Helsinki, where she received solid training in singing from Liisa Linko-Malmio and in acting from leading Finnish stage actors. By the time she was 20, she had won a national singing contest. She told Opera News that she wore pearls that she had “cultured” herself from dried macaroni.

One of her classmates at the Academy was a clarinetist and aspiring conductor, Osmo Vänskä, now the music director of the Minnesota Orchestra. “Karita is a star in everything, and that has always been true,’’ Vänskä says. “She began with a more lyrical voice that has since become dramatic, but something about her personality has always been coming out when she sings.’’

Her formal operatic debut was as the Countess in Mozart’s Le Nozze di Figaro at the Finnish National Opera. The reviews were annihilating. They said she sang out of tune; the nastiest made a point of mentioning that she was overweight. Not one to shy away from the truth, Mattila joined Weight Watchers and lost 40 pounds, which she has kept off ever since. Like Maria Callas, she knew she had to do it to become the kind of performer she wanted to be.

In the middle of the weight-loss program, Mattila unexpectedly became a star when she entered the BBC Cardiff Singer of the World Competition in Wales in 1983—and won. The competition was televised internationally, and Mattila’s charismatic looks, natural voice, and temperament made her an audience favorite from the beginning. Not one to be seduced by victory, Mattila found the voice teacher she needed in Vera Rozsa in London, and the two still work together today.

Soon Mattila was singing the major Mozart roles all over Europe and America—the Countess, Fiordiligi, both Donna Anna and Donna Elvira (her Met debut role in 1990), Ilia, and Pamina; for fun, there was Rosalinde in Strauss’s Die Fledermaus. A few conductors became fascinated by her magnetic vocal and musical possibilities; James Levine joined the parade in 1990, and Claudio  Abbado was one of her greatest advocates from the start. She always won respect from colleagues and the public, but she didn’t generate much excitement.

At Covent Garden in the mid 1980s you couldn’t take your eyes off her when she appeared as Pamina and Fiordiligi. She had a glow, even if she hadn’t figured out how to use it to illuminate anything yet. Back then, the aureate beauty of her vocal timbre was unmistakable; it had the texture of clotted cream. But she was cautious about high notes, cool about letting go.

The tone was straight, and she seemed to be skimming across the surface of her voice, a habit some conductors encouraged, always urging her not to sing so loudly in Mozart. And at that point, her legato was also not yet fully developed—the skips and triplets in Fiordiligi’s “Come scoglio” sounded as if she were punching them out on a touch-tone telephone. So not everybody liked what he heard as much as Abbado did. Mattila encountered her share of setbacks. Almost two decades later, she recalled how devastated she felt at 26 when Seiji Ozawa dismissed her from a recording of Mahler’s Fourth Symphony with the Boston Symphony Orchestra and hired Kiri Te Kanawa instead.

A more serious issue was that she sang too often, even when she wasn’t feeling well. She also admits that in her late twenties and early thirties she became a party animal. Without ever questioning her commitment to singing, she began to wonder whether she even liked opera. In the early ’90s, the accumulated level of stress and vocal fatigue required a surgical intervention in her vocal cords that might have been career threatening. What happened instead is that Mattila went shopping for a car—and found a husband, Tapio Kuneinen, who now handles many of the practical aspects of her career. She recuperated from the surgery by going on her honeymoon and returned to the stage with a new sense of purpose. “My marriage has brought me a fresh perspective,’’ she says. “Now I have something in my life that is more important than singing. That is why I can be more relaxed about performing.’’

The pivotal performance came in 1995, when she was 35. Abbado asked her to sing Chrysothemis in Strauss’s Elektra at the Salzburg Festival, promising that he would not let the orchestra drown her out. “What changed the most,’’ Mattila says, “was not my voice but my own sense of myself as a singer. I learned that my limits extended much further than I had ever thought. That performance was an explosion, but it was more mental than vocal. For the first time I felt I was singing with my whole voice, and it felt so good. I started very young, and I was very insecure as a person and as a woman; nothing happened overnight but I had grown more self-confident.’’ Vänskä says, “She’s learned to take chances and not to make excuses. Nothing about her is narrow.”

Mattila’s voice has gained in amplitude, depth, range of color; for a special effect, she can still drain it of vibrato, the way she used to sing most of the time, but the spin she can put through her tone now is thrilling. Vocal perfection doesn’t interest her as much as emotional truth; flawlessness is not the usual result of fearlessness. She always goes for broke and sometimes pays a price. But her technique is solidly grounded; she unspooled each of the long range-spanning phrases in Leonore’s demanding aria in Fidelio fluently and on one breath. Probably only Mattila and Levine were thinking about that, because of what she was using the singing for—to convey Leonore’s wrath, hope, and resolve.

The success of Elektra opened up a whole new repertoire for Mattila, not that she settled for becoming a Strauss specialist, although she became a capitivating Arabella. But she doesn’t want to be typecast vocally—or theatrically. She has sung Tchaikovsky’s The Queen of Spades in Russian, Janávcek’s Jenufa in Czech, Puccini’s Manon Lescaut and Verdi’s Simon Boccanegra in Italian, Wagner’s Eva and Elsa in German. In the Met’s Meistersinger, she looked as if she had just stepped out of a fairy tale, but the spunky reality she brought to the part was fully human. Verdi’s Don Carlos she sang in the original French in a famous production in Paris. Elisabeth has one great aria, but it is not a role that attracts sopranos; several have sung it well without leaving any trace of a character. Mattila conveyed all of the queen’s complexity and traveled her sense of duty and of principle, her sorrow and her nobility. She moves and sings with controlled abandon, but she also knows the power of concentration and repose; she delivered the whole first stanza of her aria virtually motionless, then at the reprise, let all of Elisabeth’s passion pour out.

The timing of Mattila’s career has meant that her singing has not been as fully documented on recordings as that of her predecessors; many lesser figures have recorded more. But in a way she is fortunate, because she is a creature of the theater, and television and DVD have come along to preserve the frisson of what she is like in action, in character, and before the public. Several of her signature roles are preserved on video; Fidelio and Don Carlos commercially; Arabella, The Merry Widow, Manon Lescaut, and some of her early Mozart roles circulate unofficially among her fans.

In an earlier generation, composers would have thronged to create exciting new roles for her, the way they did for Maria Jeritza or Mary Garden. That hasn’t happened for Mattila, so stage directors love her instead of composers—and she loves a few of them back (Luc Bondy, Lev Dodin, Jürgen Flimm). They think up daring or at least outrageous things for her to do; the least-gifted capitalize on her resemblance to blonde film icons from Jean Harlow through Dietrich to Marilyn Monroe. In the last act of Manon Lescaut, she arrived, exiled on the deserts of Louisiana, in a red showgirl gown modeled on the one Jane Russell wore in Gentlemen Prefer Blondes. She carried one scarlet, spike-heeled shoe in her hand. This could have looked ridiculous, but she clung onto that shoe as Manon’s one remaining link to her luxurious and carefree past, and when she cast it away, you knew it was all over for her. And she sang of her fear of death with all the vibrant desolation of an Italian verismo diva.

Mattila is as candid in conversation as she is onstage; she levels with you and her gaze does not waver. “I am talented in making enemies,’’ she admits. She has been outspoken about the patronizing behavior of some male singers, for example, while praising some of her female colleagues. In Jenufa at Covent Garden, she sang opposite the fabled Anja Silja, as original and free-spirited in the ’60s as Mattila is now. Mattila says “She is one of the few singers I can full-heartedly admire as a complete artist, and there aren’t many.” Mattila told the senior soprano how much she had learned from working with her; Silja replied, “You don’t need to learn anything.’’

Mattila’s crowded operatic calendar doesn’t leave much time for other musical activities, but she does like art songs and poetry and has made recordings of new Scandinavian songs. She has too much artistic conscience to pass off a special diva appearance as a recital, but the total package—voice, appearance, involvement—is so spectacular that there is little possibility that she can disappear inside a song, the way she can disappear inside a character onstage. Also her voice requires space to unfurl; she makes a big theater intimate, but she can overwhelm a smaller room. Songs that are narrative or dramatic suit her best—so far. And it’s hard not to share her enjoyment when she caps off an evening by swirling around the stage singing “I Could Have Danced All Night’’ as if she meant it.

Singing with orchestra allows her more scope. At Tanglewood a couple of years ago, under Vänskä, she sang Sibelius’s Luonnotar, a setting of a Finnish creation myth. The vocal and interpretive demands of this amazing 10-minute piece are extreme. The story and the music are mysterious, magical, and profound; the intervals are so difficult that the soprano for whom it was written wondered whether she could ever sing them. Flinging her arms aloft like mighty, beating wings, Mattila was thrilling in the high cries of the great frantic bird looking for a safe place to deposit the egg that will hatch into the universe. She sings it gloriously on her new Warner Classics CD recital of Sibelius and Grieg songs, but no recording can give you her presence, those long arms, those fluttering wings.

Back home in Finland Mattila is a national icon, more popular than the nation’s rock stars. She occasionally tries out a new role there, but what she really likes to do is give arena concerts. Vänskä says audiences respond the way they do at sports events. In one, the “Concert in the Snow” in 1988, the audience and the orchestra were all bundled up against the weather; you can see every frosty breath the diva expelled. She swept onstage in a dress and cape trimmed and lined with white fur, her hands in a muff, a huge snowy hat on her head. She sang the “Song to the Moon’’ from Dvorák’s Russalka, then moved on to “Don’t Cry for Me, Argentina,’’ and “Memories’’ from Cats, some of it delivered a full octave below her usual range.

For her 40th birthday she threw herself a concert in Helsinki, and more than 12,000 people came. She offered them everything from “Dich, teure Halle” from Wagner’s Tannhäuser to Adele’s “Laughing Song’’ from Die Fledermaus, as well as “Summertime’’ and “Falling in Love Again.’’ “It was far from being the most perfect singing I’ve ever done,’’ she says, “and there was no patch session to fix everything up for the recording, but I love the CD anyway because of the special relationship I have with the public in Helsinki. I shouldn’t say this, I don’t think you can go onstage or an arena concert and sing behind a music stand! What I did instead was hire a stage director and arrange for three or four costumes. I wanted to cross the huge distances of the arena and reach each member of the audience directly when I sang. Naturally some of the critics wrote that what I did was cheap, but for me it was a wonderful moment of self-strengthening. I wanted to give the public everything that I have, everything that I am.’’

That’s what a true diva does.

Richard Dyer is the music critic of The Boston Globe.