The very funny Swedish art-world farce The Square may have been a divisive pick when it won the Palme d’Or at this year’s Cannes Film Festival, but there was one thing the entire international film community could agree on: the swooning. Claes Bang, the movie’s dashing and virtually unknown Danish star, might as well carry a fainting couch with him, considering how often he inspires fawning reveries from anyone who sees him, onscreen and off. “The main actor, I felt in love, I must say, and I’m not the only one,� said French actress-director Agnés Jaoui when asked at a press conference why she and other Cannes jury members had given The Square their top prize. “Yes! Yes!� enthused Will Smith, who’d been sitting next to her.

All eyes had been on Bang at Cannes because all eyes had been on The Square, director Ruben Östlund’s first film since his wickedly awkward “avalanche comedy� Force Majeure, in which a man abandons his family to save himself during a terrifying snow slide (that turns out to be just a scare) and then has to continue on a five-day ski vacation with them. Certain men I know still shudder involuntarily anytime anyone brings it up. Östlund is once again mining themes of failed masculinity, only through the lens of Bang’s Christian, the handsome, arrogant curator of a Stockholm contemporary-art museum whose avalanche comes when he gets robbed of his wallet and phone by a woman he thought he was helping — sending him on an insane quest for revenge that soon has him betraying everything he thinks he stands for.

“I think with this part, I got to drive a Rolls-Royce of acting. I can’t imagine an actor in the whole world who wouldn’t kill his family to do this part,� says Bang, sitting across from me in a Toronto restaurant. He got to do comedy; speak extensively in English; show off his electronic-music-dancing skills; have very sweaty sex (and a condom tug-of-war) with Elisabeth Moss’s reporter character; interact with a monkey; dig through garbage in the rain; play a loving and fallible father; give grand speeches about the meaning of art; verbally spar with an irate 12-year-old; and have not just a fall but a complete face-plant from grace. “One of my agents said, ‘This is the best show reel I’ve ever seen! If someone phones me up and says, Can Claes do this?, I’ll just pick a scene from the film and send it,’� Bang goes on. “Apart from blowing something up or shooting someone, I’m pretty much covering it all.�

Comparisons to Pierce Brosnan and Jon Hamm, but funnier, come to mind. Bang is six-foot-four with a great head of dark hair and an air that suggests he takes his martinis shaken, not stirred. He’s also spent the past 30 years plugging away in theater and TV in Denmark and Germany, and in a Scandinavian crime series called The Bridge that aired on the BBC. And watching him for the first time, at age 50 — commanding the tricky tone of the biggest opportunity of his career — sparks the same kind of “Where have you been?� awe that so many felt upon seeing Hamm emerge as Don Draper at 36. Or, perhaps, Bang’s fellow Dane, Mads Mikkelsen, now 51, although he’d had way more international success by the time he landed NBC’s Hannibal four years ago. (Surprise, surprise: Getting to emerge as a sex symbol at 50 is a very male privilege, though let’s not begrudge the unwitting beneficiary.) Even Bang can’t believe this is happening to him now. When I tell him I want to introduce him to readers who don’t yet know he is, he laughs. “Obviously they won’t. I don’t think anyone would’ve seen me anywhere!�

At least once people learn his name (pronounced CLAY-ss, plus the sound a gun makes), they aren’t likely to forget it. He assures me it’s standard issue in Denmark, even if it reads like it’s something made up for a comic book or an adult movie here. “A superhero porn star! That’s great! I can connect with that,� says Bang when I tell him exactly that. Every time he shows his passport at U.S. border control, he says, “They look at it, and it’s like, ‘Really? Are you sure you’re called Bang? Is that a joke?’� His full name is Claes Kasper Bang. He’d asked his new American agent if he ought to just go by Claes Kasper to avoid the fuss, and, says Bang, “He was like, ‘No! Don’t do that!’ It was a pretty short conversation. I just didn’t want people to think, Here’s this idiot Danish actor who made up this name to get attention. It’s really quite common here, and I’ve had it all my life.�

Bang beat out some 150 actors for the part, weathering a massive casting search that went through all the Scandinavian capitals — Copenhagen, Stockholm, Oslo, Helsinki — and into London. Östlund had been open to casting an English speaker in the lead, since top posts at museums and operas are often international jobs. Bang tells me he got his American agency, UTA, after some of the agency’s famous British and American clients didn’t get cast and they wanted to know who did. (Neither he nor Östlund is naming names, but they were big enough to make Bang lose all hope of getting cast, which he’d already thought was a pipe dream, given that Force Majeure had been a big-enough deal that Östlund could have had his pick of anyone.)

“Claes was a surprise to me as well,� says Östlund. “He’s not known in Sweden, either, and not that known in Denmark.� The casting process was multiple two-hour sessions of workshopping scenes from an unfinished script. What made up Östlund’s mind was a speech he’d asked his finalists to write introducing the movie’s central art exhibition — a literal square in a public plaza that’s meant to be “a sanctuary of trust and caring� — to a crowd of donors. Bang’s speech is in the movie almost verbatim. “He said, ‘My father just died and I have no one to talk to. Can you talk to me for half an hour?’ And that was really touching,� says Östlund. “That was pretty much the moment I decided on Claes. He was able to bring some emotion to this very intellectual, conceptual idea.�

Bang doesn’t have writing experience; he just loves going to museums. And Östlund’s thought process was a complete mystery to him. “It’s funny,� Bang says, “because after a couple of hours of improv, Ruben said ‘Thanks’ and was about to send me on my way, until I said, ‘What about that speech I’ve prepared?’ Good thing I insisted on doing it.� Months of callbacks went by, all while Bang kept hearing that Östlund was seeing other people. Bang was actually onstage during a run-through of a Danish play when he heard his phone ring in his bag with the call from Östlund, which he’d known was coming that day. “And I had to wait an hour until we finished the play!� he says. “Then I picked up and found out, and I was jumping up and down. I was literally doing exactly what you would expect a person to do.�

Whatever Östlund saw in Bang’s audition may have something to do with how he had to find art on his own, coming from a family of businesspeople where he’s, he says, “the black sheep.� He caught the acting bug during a high-school production of Hair and eventually spent four years of rigorous study at the Danish National School of Performing Arts, which at the time admitted only eight students a year from a pool of 600 applicants. Now he lives in Copenhagen with Lis Kasper Bang, his wife of seven years; they met when she did his makeup on a theater production. She invited him to her 41st-birthday party, “and I actually never left,� he says. “All of a sudden, this new guy took all of the guests to the door. ‘Look, you need to leave now. Bye-bye!’ And I’ve been with her ever since. I was her birthday present! A bit embarrassing, but also quite funny.� In his spare time, he composes, produces, sings, and plays all the instruments for his side gig as an electronic-pop musician. When we met up, he was wearing a T-shirt emblazoned with the image of his idol, David Bowie; he stole the name of his one-man project, This Is Not America, from one of Bowie’s tracks. His music can be seen in the trippy black-and-white videos he’s been putting out on YouTube since 2008, including one with him in a wig and drag makeup.

Fun fact that non-Scandinavians probably won’t pick up on: Bang speaks Danish in the film, but almost everyone else, except for Moss, is speaking Swedish. It’s the kind of thing that could happen in real life; most Danes and Swedes can understand the other’s language. And the movie takes place in an alternate reality in which the Swedish monarchy has fallen. The museum where Bang’s character works is called X-Royal, and its exterior is the actual Royal Palace in Stockholm. (The backstory Östlund cut from the film is that the king attempted to reach out to the people via a monarchical YouTube channel, and it went horribly wrong. This is apparently based on the real Swedish king Carl Gustaf XVI’s being terrible at press.) Bang’s character is named after a Danish king from the 1500s, Christian II, who took over the palace in Stockholm and decapitated everyone inside it. “That’s why we thought it would be fun that the next time a Danish guy came to that castle, he’d be called Christian too,� says Bang. Unsurprisingly, they were not allowed to shoot inside the palace.

Bang hadn’t even read the script by the time he got the part. Östlund likes to find his dialogue through an intense trial-and-error process that makes David Fincher sound like a pushover. The Square shot for 78 days. Most mornings would begin with the actors and Östlund improvising a scene until Östlund felt the dialogue seemed natural, at which point Östlund would “lock� the script and then start shooting what they’d workshopped again and again. “He wants to see if he can get it in one take, so that means that you go through the whole scene for every take, which could easily be seven, eight, nine minutes every take,� says Bang. “Then he’ll probably do something like 60 or 70 of those. It’s exhausting in that around take 20 or 25, you sort of lose your consciousness. You stop wanting, intellectually, to do something with the scene.�

Moss, who arrived ten days before the end of the shoot, says she and Bang bonded immediately while shooting the movie’s opening sequence. “He’s a brilliant actor,� she writes by email. “You trust him, but you’re never sure what’s coming next.� She plays a not-so-good reporter trying to get Christian to explain self-serious art stuff in normal human terms for an on-camera interview. What made the final cut is only two questions long, but they spent hours going back and forth. To prep, Bang memorized a transcription of a half-hour interview with an actual Stockholm museum director, which he then had to regurgitate, in his own way, in response to whatever Moss gave him — while also flirting with her ever-so-slightly, since that comes up again halfway through the film. “At that point,� says Bang, “I could answer any fucking question you could ask me as a museum director, because we’d just rehearsed so much. I could talk about economics, how you fund a museum, anything.�

Bang sounds as if he was game for any torture Östlund had for his character. He didn’t just dig through a pile of garbage; he did it for two days in the rain. He didn’t just have scenes with a monkey who randomly lives with Anne, Moss’s character; he did it while absolutely terrified, because the monkey came with instructions not to sing, yell, or run around it, lest it become unhinged. During his sweaty sex scene with Moss, he was lying on a bed as a cinematographer sat on top of him, gyrating with a camera, to create a more realistic POV. (For her shots, Moss gyrated on top of the cinematographer.) During the scene when Christian and Anne get into a tug-of-war over who’s going to throw away the condom — he’s clearly afraid she’s going to do something sneaky with his sperm — Bang tried a take where he ate it. “Well, I didn’t swallow it, but a little bit of it was sticking out of my mouth and she was trying to get it out. We were laughing so hard after that.� Later, he somehow managed to keep a straight face during a scene in which Anne confronts Christian about their night together (Östlund insisted that she keep repeating the words “You were inside of me�) while standing in front of a museum installation of a teetering pile of chairs that could crash to the ground at any moment. “Ruben had a button,� says Bang, “and when he could sense that this would annoy us most, he’d push it!�

Since Cannes this May, Bang says he’s had some 50 scripts come his way, including two British thrillers and a big Hollywood production he’s excited about. In a normal year, he’d get maybe five film and TV scripts. But he’s trying to be picky. “I’ve been an actor for 30 years,� he says. “I’m not going to run from a great theater production to do two days on an HBO series or something.� True to his word, he’s just finished doing a Danish translation of British playwright Martin Crimp’s The City and will soon film a Danish-TV Christmas special. He’s also amped up his side gig and has been recording electronic-music tracks — one is coming out commercially — with Swedish synth-pop legend Marina Schiptjenko, whom he met when she played his boss on The Square. His dream is to work with David Lynch, Michael Haneke, Alejandro González Iñárritu, or Toni Erdmann director Maren Ade (he’s fluent in German), and he cryptically hints that some of those projects he’s excited about may align with that dream. “Obviously, this film has opened up some opportunities for me, because there are people out there who didn’t know that I was here, and now they do, and now they might want to use me,� he says. “And that’s really supercool.�

*A version of this article appears in the November 13, 2017, issue of New York Magazine.