Frank Grillo has an insatiable appetite for flexing his movie muscles.

The actor is superhumanly prolific, practically cornering the market on macho roles as he veers from facing off with Captain America in “The Winter Soldier” to entering the ring with Nick Jonas in “Kingdom.” Since 2014, the 55-year-old Grillo has starred or had a supporting turn in 30 films or television shows, eight of which are scheduled to debut in 2021 alone. But he insists that he’ll hang up his spurs the second he stops feeling a thrill when he sees his name in lights or his face on a billboard.

“The day that isn’t cool is the day you should ride off into the sunset and stop doing it,” says Grillo. “It’s pretty magical to be able to make movies. It’s pretty magical to have people come up to you and say, ‘Hey, you were great in this or you made me laugh or you made me cry.’ I wake up every day grateful and thankful that I got this far. That’s no bullshit.”

Maybe it’s his work ethic, the product of a blue-collar upbringing, or his nagging fear that the phone will stop ringing if he doesn’t stay active, but Grillo is everywhere these days. He’s appearing in low-budget indies like the recently released “No Man’s Land,” as well as action flicks like the upcoming “Boss Level” and “The Hitman’s Wife’s Bodyguard,” a follow-up to the 2017 hit “The Hitman’s Bodyguard” that finds Grillo playing an Interpol agent opposite Samuel L. Jackson, Salma Hayek and Ryan Reynolds. And he’s formed a production company, WarParty, with his frequent collaborator and “Boss Level” director and writer Joe Carnahan, with whom he partnered on “The Grey” and “Wheelman.” The goal is to make the kind of testosterone-drenched action movies that dominated multiplexes during the ’80s and ’90s but have been relegated to the ash heap by major studios in favor of superhero spectacles. Their pitch to financiers and distributors is that they can deliver big set-pieces and thrills more efficiently and for a reasonable price.

“I’ve been struck by how absurd the amount of time we spend prepping films has become,” says Carnahan. “You go back to the old studio system, and they would prep a film like ‘Casablanca’ in a couple of weeks and shoot it in a couple more weeks. I find nothing wrong with that approach. We’ve conditioned ourselves to need a year or a year and a half to make a movie, and that’s become the norm, but I just find it wasteful.”

In the case of “Boss Level,” the story of a special forces officer ensnared in a time loop that causes him to repeat the same day, the producers shaved 15 days off a planned 41-day shoot to get the movie made. It was a punishing experience, one that found Grillo dodging explosions, engaging in intricate sword fights and consistently putting his body in the line of fire (OK, they were blanks) while filming sequences in one afternoon that would normally take days to produce. Grillo, a skilled boxer and an inveterate gym rat, trained for six months to get ready for the role.

“I’m an athlete and a fighter, and I have to be as truthful with the action as I am to the words in the script,” he says. “A lot of actors will talk about ‘Oh, I gained 40 pounds for this role.’ Well, that’s not so hard. I could gain 40 pounds. How about going down to 4% body fat? Pulling off the physical part of a film like this is very underrated and very hard to do.”

Grillo waited for years before he got his big break, appearing in commercials for beer and deodorant along with a few blink-and-you-miss-them roles in “Minority Report” and the like. That break came with 2011’s “Warrior,” playing Joel Edgerton’s friend and trainer.

Shortly after the film was released, director Gavin O’Connor fielded several calls from filmmakers and agents wanting to know who “that guy” was.

“There’s a danger to Frank, and it just comes off of him,” he says. “He has a street fighter attitude, and you sense he has some miles on him. He’s like a pit bull with a handsome face. And that’s unique. There’s not a lot of actors like that.”

Grillo was north of 40 when he achieved big-screen success, and he thinks that the long wait helped him keep his feet on the ground. He’s wary of the Hollywood scene, both its corporate mandates and its system of star perks. That skeptical view of the business helped him bond with Carnahan.

“We’re not Hollywood guys, and we don’t go for the parties or the premieres or the trappings and the bullshit that Hollywood has to offer,” says Grillo. “We’re just normal dudes who happen to make movies.”

“Boss Level,” which plays like “Groundhog Day” with a much, much higher body count, debuts on Hulu on March 5. Carnahan hopes that he can make a film every year or two with Grillo; the pair quickly followed “Boss Level” with “Cop Shop,” a thriller that unfolds in a rural police station and finds the actor playing an oleaginous con man, complete with a man bun. Gerard Butler will play his adversary, a hit man who forces him to seek protection from the cops. The film, which is in post-production, was shot after the coronavirus upended the movie business. To pull off the shoot, WarParty worked with veterans of Doctors Without Borders who had operated in pandemic-ravaged areas to create a system of best practices. Cast and crew were put into working pods, tested every other day and discouraged from socializing between takes — craft-service stations were even abolished entirely.

“You can’t really do a socially distanced fight scene,” says Grillo. “But I felt safe knowing that the other actors were taking the same precautions I was.”

In fact, Grillo says that the COVID protocols made the shooting more efficient. “There’s too much socializing on sets,” he says. “That results in a lot of wasted time. This was much more streamlined.”

“Cop Shop” also got Grillo out of the house and back in front of cameras, after months stuck at home in quarantine. He was feeling restless and bored, while grappling with a divorce from Wendy Moniz, his wife of two decades.

“If I’m not working, I’m going stir crazy,” says Grillo. “I always feel like if I don’t work, the offers are going to stop or the opportunities are going to dry up. I still have that poor-kid mentality, and I don’t think it will ever go away.”

One silver lining of the whole COVID experience has been the surge in interest in “Kingdom,” a show about the Kulinas, a family of MMA fighters, that was critically beloved but low-rated during its three years on DirecTV. The show wrapped up in 2017 and may have been relegated to obscurity had Netflix not decided to license it. With much of the world in lockdown, audiences that had never heard of “Kingdom” embraced the show, following the trials and tribulations of the Kulina clan over the course of 40 episodes.

“It is the greatest thing that’s happened in my career,” says Grillo. “I always thought that show was beyond underrated and unrecognized. It was a sin. We worked hard on that show physically as well as artistically. But DirecTV really shit the bed. It didn’t know what it was doing and still doesn’t know what it’s doing. It had no business being in the business.”

In the months since “Kingdom” developed an avid following, fans have pushed for a fourth season, with creator Byron Balasco even hinting that the show could be revived. Grillo isn’t so sure.

“We’re all in different places four years later, and we’re doing different things,” says Grillo. “The idea of it would be awesome, but I think the show ended perfectly. I really do. It ended the way it should end, and to try to come back and try to recapture lightning in a bottle is a very dangerous thing.”

And don’t hold your breath for many more appearances in the Marvel Cinematic Universe after Grillo lends his voice to “What If … ?,” an animated series that will find him re-creating his role as the villainous Crossbones. The character is a staple in the Captain America comic books but largely a bit player in the movies. Crossbones was killed off in “Captain America: Civil War,” and even though dead characters have a way of being brought back to life in comics, Grillo thinks his alter ego will stay six feet under.

“They’re done with me,” he says. “Because of the way the stories wound up being told and just how big the stories became, the Crossbones of it wasn’t really part of the future of the Avengers.”

Grillo does hope to keep stretching himself. Over the past decade, he’s assumed the mantle of a big-screen brawler, taking the kind of roles that previously would have been played by a Kurt Russell or a Sylvester Stallone as easily as he would a well-worn muscle shirt.  He’s also eager to avoid being pigeonholed; hence one of his upcoming projects, the indie crime drama “Ida Red,” finds him playing very much against type as a gay man whose wardrobe includes mesh shirts and cowboy boots.

“I don’t want to just be the guy from ‘The Purge,’” says Grillo. “It’s OK getting typecast if they’re paying me well, but I’m still going to seek out those little movies, so I can flex different muscles, get better and better, and put more characters under my belt.”