Even before cameras rolled, Carrigan had “everyone on set laughing,” says executive producer and star Bill Hader, who was also directing his second scene ever. The crew was parroting NoHo Hank’s lines. Hader recalls saying to his co-creator, Alec Berg, “We’d be nuts to kill this guy off. He’s just too funny. Why would we get rid of him?”

Instead, NoHo Hank took a bullet in the arm. “We let him live,” Hader says by phone. “Now, he’s a huge part of the show.” NoHo Hank survived to malaprop another day and the scene-stealing Carrigan went on to appear in every glorious episode of “Barry,” deemed 2018′s best show by The Washington Post’s Hank Stuever. The third season returns Sunday after an almost three-year hiatus due to the pandemic. NoHo Negronis were served at the L.A. premiere Monday night.

Before the plot-twisty new season, HBO has issued a lengthy do-not-reveal list that rivals the redactions in the Mueller report. So much, dear viewers, cannot be disclosed. However, NoHo Hank features prominently. His singular spin on the English language and American pop culture continue to elicit chef’s kisses. To wit: “See you on the flippy flops.” And, yes, there are revelations about Hank’s personal life.

“It is easily the best role of my career, the most fun and rewarding,” says Carrigan, 39, perched in a Lower Manhattan cafe during a trip to visit friends, attired in loose clothing drenched in primary colors, sartorially distinct from NoHo Hank, who is partial to too-tight slacks and pastel polos. “There’s a purity to Hank that doesn’t even exist in any of the show’s other characters.”

NoHo Hank is based partially on, of all creatures, an Apple Genius bar technician who repaired Hader’s laptop while he was writing the series. “He was very friendly and incredibly helpful in every possible way,” Hader says by phone. So he imagined that personality as a murderous Chechen mobster. “Most bad guys don’t think they’re bad guys.”

“Hank is so sunny, so positive, so eager to please instead of the cliche of the dark, brooding, violent guy,” Berg says. “He just wants to get people a sandwich.”

The series has brought Carrigan an ardent following (a YouTube reel of NoHo Hankisms attracting almost 1.7 million views) and an Emmy nomination.

“I feel like my career is essentially two different careers,” he says: Hair and No Hair. No Hair, though it’s confined him to villain roles according to the bizarre, immutable rules that govern the entertainment industry, has been infinitely better.

At age 3, Carrigan was diagnosed with alopecia areata, though the hair loss didn’t fully progress until his late 20s. Raised in the Boston suburb of Winchester, Mass., the child of parents who performed in regional theater, Carrigan was not concerned that his acting roles might be limited and decided to study at Carnegie Mellon’s vaunted drama program.

Alopecia is the autoimmune disorder shared by his fellow “Gotham” actor Jada Pinkett Smith — they minimally crossed paths on set, Carrigan says — who was the target of the paltry Chris Rock quip that ignited the Slap, inspiring several thousand columnist takes and getting Will Smith banished from the Oscars until he’s eligible for Social Security.

Asked about that incendiary moment, Carrigan says, “Anyone who thinks it’s just hair has no idea of what the impact it has on your self worth. Everyone got activated. Everyone got triggered by it. Because every alopecian has experienced teasing, bullying comments, stares.”

Still, “one positive thing [that] came out of the Oscars is that everyone is learning about alopecia,” says Carrigan, who works with the Children’s Alopecia Project. “It was googled more than it’s ever been googled,” he says. Searches spiked 2,950 percent in a day, according to the search-engine behemoth. In the past year, Carrigan has been the fourth-most-searched person with alopecia after Pinkett Smith, Rep. Ayanna Pressley (D-Mass.) and the late Superman actor Christopher Reeve.

Once Carrigan was another Hollywood Handsome Guy with hair. Then, for two years, he was another Hollywood Handsome Guy pretending to have hair, sporting wigs, hair pieces and eyebrows crafted with a makeup pencil. He used a cream for a while that caused a painful reaction similar to poison ivy.

Carrigan landed regular if not particularly indelible work, such as the ABC drama “The Forgotten.” He played Adam Braverman’s stoner jerk of a sneaker company boss on the more memorable “Parenthood.” A villain, of sorts.

Hiding his alopecia became a second job. He worried that once it was discovered, the work would stop. Carrigan was drowning in a sea of stress, which only exacerbated the hair loss.

“I was terrified, initially. I thought I was going to be annihilated,” Carrigan says. “When you have such a deep-seated fear of something happening, that’s what you think: ‘It will destroy me.’”

Directors did notice. The camera caught everything. “That period of my career is very trying. Acting requires a lot of vulnerability. It requires a kind of openness. It’s a weird thing to try to be open while hiding at the same time,” he recalls. “It created a schism in me. I went through a massive amount of stage fright.” Which bonded him later with Hader, who also suffered from profound anxiety before audiences while he appeared on “Saturday Night Live.”

That’s when he thought his career might be over. But finally, Carrigan decided to come clean about the alopecia and own it. He sought new representation. A mutual friend called Carrigan’s eventual manager, Colleen Schlegel, to explain the situation. She recalls saying, “If he’s okay playing bad guys, send him over.” Carrigan headed over.

“In Hollywood, we’re so ‘creative’ that a bad guy needs to have a British accent, smoke cigarettes or have a bald head,” Schlegel says.

No Hair Carrigan landed work: Kyle Nimbus (a.k.a. the Mist) on the CW’s “The Flash,” Victor Zsasz on Fox’s “Gotham.” And, finally, “Barry.”

And, here, a splendid irony: A gangster is barely a villain on a show where, as Carrigan puts it, “all the characters are kind of awful in their own way.” NoHo Hank’s perpetually joyful disposition provides comic relief when matched with Barry’s scowling prince of sharpshooting darkness. “Barry finds him annoying, and NoHo Hank thinks of him as a close friend,” Berg says. To him, everything is “super great” and “ciao, babies” or “you know what Sonny and Cher say, ‘That’s on you, babe.’ ”

Review: Terrific ‘Barry’ shows how HBO’s best dramas are often found in its comedies

“From the beginning, we talked about the two worlds that Barry is in,” Berg says. Barry is a very good assassin who wants to be an actor and, initially, isn’t a good one. “The crime world has very, very high stakes but very low drama. While the drama world is very, very low stakes but very high drama. NoHo Hank is not worried about life and death. He’s worried about Barry being happy.” Berg imagines NoHo Hank learning English as a child watching way too much of Chechnya’s equivalent of TV Land.

For the role, Carrigan sought a dialect coach. He kept a gratitude journal as his character — NoHo Hank is a grateful mobster — and took to commenting, in that accent, at all the Los Angeles wonders that delighted him on the drive to work. “With comedy, you have to play it as dramatic as possible. The circumstances that you’re leaning into just happen to be ridiculous but you have to take the character very seriously,” he says. Carrigan lives in the L.A. area but unlike his character, not in North Hollywood. “I am not a method actor.”

Burning question: Is NoHo Hank, who says many silly things and does many foolish things (like sending a bullet via DHL), intelligent? “He’s really smart,” Berg says unequivocally. “He’s just incredibly eager to be helpful and wants everyone to be okay. We always thought of NoHo Hank as the nicest guy on the block.”

Carrigan feels liberated by the work and his embrace of alopecia. “I feel so much lighter. I feel so much freer. I’m not bound by it anymore. I got better parts,” he says. “When I stopped hiding, I think I became the actor that I was meant to be. I felt like I could be present for the first time and not be worried about anyone noticing the eyebrows or the eyelashes.”

Hader concedes: “I’ve never seen any of his performances with hair. I don’t really think about it,” he says. What nailed Carrigan’s audition for Hader and Berg was how well he listened, that he grasped the character without saying a word. “Anthony is so chill and so incredibly open to everything,” says Hader, who is known for breaking character (see SNL’s Stefon). “He breaks me up. I’m a very soft touch.” In the sixth episode of Season 2, Carrigan caused Hader to repeatedly break character as they’re both surrounded by Chechen mobsters and accompanied by an accordion.

Meanwhile, Carrigan has completed work on his first animated series. He’s prohibited from saying much about this one either except that it’s scheduled to air later this year.

Yes, even animated, he plays a villain, but he’s excited. He’s passed on several auditions for mobsters, some of them Russian. “I can do so many other things. I feel like I’m capable of so much,” he says. “But Hollywood doesn’t have too much of an imagination, ironically.”

His manager Schlegel nurses high hopes. “If I could stop the villain train, that would be awesome,” she says. “I’ll feel my work is done when Anthony gets a romantic lead.”