The actor talks about his roles as a failed superhero in the new Marvel blockbuster and as a milquetoast accountant in Steven Soderbergh’s “No Sudden Move.”This article contains spoilers for the films “Black Widow” and “No Sudden Move.”It’s never a particularly good time to be a loser, but it’s an excellent moment to be David Harbour, who embodies misbegotten characters so fully in his latest movies.Harbour, who may be best known as the reluctantly heroic police chief Jim Hopper on Netflix’s “Stranger Things,” can currently be seen in “Black Widow,” the Marvel movie directed by Cate Shortland that opened over the weekend. In it, he plays Alexei, a Russian super-soldier who formerly led a thrilling life as the costumed champion Red Guardian. Now confined to a wintry prison where he has become feral and overweight, all he can do is reminisce about good old days that may not have happened as he remembers them. That is, until his rescue by Natasha Romanoff (Scarlett Johansson) and Yelena Belova (Florence Pugh), the spies he raised as his own daughters.Alexei is the latest in a series of strangely compelling deadbeats for Harbour. He also appears in Steven Soderbergh’s new HBO Max thriller, “No Sudden Move,” as Matt Wertz, a milquetoast accountant drawn into a criminal enterprise that’s well out of his league.And these are precisely the kinds of characters that Harbour loves to play. As he explained in an interview on Thursday: “Winners are great, and we like them, rah-rah. But to me, the beauty of human beings is in the flesh and the failures. We’re all frail.”Having performed over the years in Broadway productions of “Glengarry Glen Ross” and “The Coast of Utopia” as well as in films like “Brokeback Mountain” and “Revolutionary Road,” Harbour called his current renaissance “another step in a very even-keeled, slow trajectory, which I like.”Now 46 years old and married to the pop singer Lily Allen, Harbour said he was happier to have found success at this stage of his life. If he’d had this much attention as a younger man, Harbour said: “Oh God, that would be miserable. It took me so long to cultivate an artistic voice. If I had people judging me so early about whether or not they liked what I did, I wouldn’t be able to survive that.”Speaking via video from New Orleans, Harbour talked further about the making of “Black Widow” and “No Sudden Move,” his offbeat influences and the comfort of working with Soderbergh during a pandemic. These are edited excerpts from that conversation.Harbour with Scarlett Johansson, left, and Florence Pugh in “Black Widow.”Jay Maidment/Marvel/DisneyIs there a story behind how you were cast in “Black Widow”?It’s oddly pedestrian. I have friends who tested for “Guardians of the Galaxy,” who talked about a top-secret lair and getting sides [dialogue pages] and then they burn them. My agent said Cate Shortland wants to meet you for a movie she’s doing. He didn’t even know what it was about. I sat down with her, and she said, “I’m doing this ‘Black Widow’ movie for Marvel with Scarlett Johansson.” And then she proceeded to pitch my character as this dude who’s big and violent with tattoos and gold teeth and also needs you to like his jokes. She pitched me these incredible contradictions, and we talked about all these family dramedies with desperate people — movies like “The Savages” and Ricky Gervais on “The Office.” And I was like, hell yes, on so many levels.Please, elaborate on the Ricky Gervais connection.It’s just that he’s so desperately insecure, and that insecurity manifests itself in boastfulness. I love people like this. He now has such deep regret and emotional guilt, but he can’t feel any of those things. So all he does is exist on his sociopathic charm and his need for validation. Someone like Hopper [in “Stranger Things”] has guilt, but it’s so internal, whereas he’s loud in every way. Smelly and sweaty and big and hairy. So cringey, as the kids say.Is it flattering to be told by a director that she sees you as this person?I have such an odd ego. I am always flattered, and then I look back years later and I go, what were you flattered by? I’m sort of an outcast myself. Growing up, I was, certainly. And I’ve always wanted to act because I wanted people to feel less alone. Even when I’d play villains, people would say, “There was a way that you humanized the experience so that we understood someone, as opposed to judging them.” So that’s what flatters me — you’re using me as an artist to understand this deeply troubled and confusing individual that a less capable person would make a mockery of. I maybe proceed to do both. But I can hopefully give you some understanding of him.Had you ever worked with Johansson, Pugh or Rachel Weisz, who play the other members of your makeshift family?I had never even met them. But then we had rehearsals for about two weeks, which is rare on a movie this size, and we really did take on those family dynamics, right from the get-go. I did feel like Rachel was the woman I was meant to be with — no offense to Lily Allen, because she is the actual person I was meant to be with — but it did feel like Melina and Red Guardian had something beautiful. Scarlett felt like the oldest child; I started to see her as rigid in a certain way, and I started to poke fun at her rigidity. And Florence really felt like the baby of the family; I just wanted to coddle her and make her laugh.Which did you film first: the prologue scenes where your character is neat and trim, or the main sequences where he has gone to seed?I had grown the beard and the hair for “Stranger Things,” and I was like, “Let’s use the weight.” So I started eating even more. I got up to 280 pounds, and I loved it. I said to the first A.D. [assistant director], “Listen, we have to shoot the flashback stuff at the end, so that by the time we shoot the flashback, I’ll lose the weight and I’ll be thin.” And he was like, “You’ll never be thin.” [Laughs.] I was like, “Yes I will, man.” And I lost like 60 pounds through the shooting. The first stuff we shot was at the prison, so that belly that’s coming at you, that’s all real belly. And then as we shot, I started to lose weight. I was just hungry a lot of the shoot.”I’m the anti-Tom Cruise” when it comes to stunts, said Harbour, with his four-month-old puppy.Akasha Rabut for The New York TimesYou’re a recently married man — how was all of this physical transformation playing at home?[Dryly] It’s a true testament to my undeniable charisma when I say that my wife met me at 280 pounds with this beard and this hair. We went on a date at the Wolseley [restaurant] in London, and she really fell for me at my worst, physically and hair-wise. So as the thing went on, I started losing the weight and working out. And she honestly has some mixed feelings about it. Which is a good place to be in a relationship. It’s really good to start the relationship from that part, as opposed to being the young, handsome buck and watching yourself degenerate over the years.Did you get to do many of your own stunts on the film?They really want you to do it. They’re very encouraging. But I’m the anti-Tom Cruise when it comes to this stuff. I do not want to fly the helicopter. I want Alexei to be a production of eight different people. I’m the face. I’m very happy to put the stunt people in. But I do my own arm-wrestling. I wouldn’t let anyone else arm-wrestle for me.Your best-known characters now are men who, underneath their exterior shabbiness, possess at least the potential to redeem themselves. How did this come to be your particular turf?That’s what I love about Alexei and what I love about Hopper. It comes from my view of Walter Matthau. In “The Taking of Pelham One Two Three,” you have this schlubby leading man and you put him against Robert Shaw, who’s like the most bad-ass Brit in the world. You think he’s never going to take this guy. But there’s something about his American heart that we want to love, and I love embodying that. Once Hopper rolled around, it was like, swing for the fences. Give him the dad bod and let him smoke cigarettes, have him be a total mess.Just a few years ago, you were playing a lot of intimidating bruisers and flat-out villains. How did you pivot from that?It was very interesting to be perceived as a villain. There were heavies, but then I was cast as true, dangerous psychopaths, too. There’s something about the mental freedom of the psychopath that I can embrace in a certain way. It really was [the casting director] Carmen Cuba on “Stranger Things” who was like, “I know this guy’s been the villain and he’s been fifth and sixth on the call sheets for a long time, but I think he’s the Harrison Ford.” No one had seen that before. I always blamed it on the jawline or the brow, whatever it was. It really takes a sophisticated eye to go, it doesn’t matter whether he has a double chin. His heart is there.Harbour as a milquetoast accountant opposite Amy Seimetz in the new Steven Soderbergh crime drama, “No Sudden Move.”Claudette Barius/Warner Bros.How did you get your part in “No Sudden Move”?It got shut down during Covid, so they refashioned it and put that movie back together. A couple people couldn’t do it so a couple replaced them, and I was one of them. Steven Soderbergh’s process is very simple: He sent me the script. Would you like to do this? Yes, very much. And then I met him on the first day.Going by only the screenplay, what was your read on the character?Matt lives in a prison of his own making. The tragedy of Matt is that he can’t be who he is, and he’s been living this lie for a long time. There is a carrot that gets dangled in front of him, and as one of the characters says in the movie, he had the brass ring and he just let it go by. That’s the true tragedy of Matt Wertz. There’s some excitement that he may actually get to live a life, finally, after so much struggle. And he disappoints us. [Laughs.]Was this the first film you made during the pandemic?That was my first pandemic shoot. “Stranger Things” had come back for Season 4 in September, and they didn’t need me until January. And I freaked out. I love my wife and kids, but I also need to go to work, because I’ll lose my mind here, trying to home-school them. This job came to me, and I took it. We were in Detroit for two and a half, three months, sequestered in a hotel. But luckily it’s Soderbergh. He did “Contagion.” So all the C.D.C. guys that he worked with on that were there on set. We were talking about the vaccines. I would go to Soderbergh and be like, “When is this going to be over?” And he would be like, “Oh, sometime early next year, there’ll be vaccines.” I was like, “Which one?” He’s like, “Pfizer’s doing very well — two shots.” It was incredible. You’re making this movie and you’re finding out what’s actually happening at the C.D.C.Harbour on being asked to play losers: “I have such an odd ego. I am always flattered, and then I look back years later and I go, what were you flattered by?”Akasha Rabut for The New York TimesWhat are you permitted to say about the new season of “Stranger Things”?Ugh. I want to tell you something. I have my prepackaged answer, which is true, that it’s a super-exciting season. It’s gone to a whole other place. It started out, in Season 1, with this small-town police chief, and now it’s become this sprawling thing with a Russian prison and a monster. The brothers [series creators Matt and Ross Duffer] are big into video games, manga and anime, and we definitely play on that this season. We talked about “The Great Escape” and “Alien 3” as influences. In terms of Hopper, you get to see a lot of back story that you haven’t seen before, it’s only been hinted at. As opposed to this dad he’s become, eating chips and salsa and yelling at his teenage daughter, you’ll unearth some more of the warrior that he had been.Having now made a mega-budget Marvel movie, was there anything you could take from that experience into “Stranger Things”?I do a lot more stunts this season than I’ve ever done. And I — if I do say so myself — did some pretty impressive things. And that truly came from being humiliated on the set of “Black Widow,” being not able to do those things. There is an ego in me that’s growing. Hopefully by the time I’m 55, I’ll be hanging out of a helicopter as well, making my own version of “Mission: Impossible.” More