There are few purveyors of intense, unhinged absurdity and compelling over-confidence as powerful as Jason Mantzoukas. The actor has carved out a niche playing uproarious oddballs in TV shows like The League, Parks And Recreation, Brooklyn Nine-Nine, The Good Place and Community, and films such as The Dictator, Bad Neighbours, The House and Dirty Grandpa. Thus, it’s somewhat surprising to find Mantzoukas in the dazzling, gory and frenetic action thriller John Wick: Chapter 3 – Parabellum, which finds Keanu Reeves reprising his role as the titular assassin, who’s forced out of retirement after becoming the target for contract killers across the world.

Mantzoukas plays the homeless Tick Tock Man whose invisibility in society allows him to work for the influential Bowery King (Laurence Fishburne). But the John Wick franchise has always had a deadpan wit that complements its deliberately excessive violence, and that combination meant that Mantzoukas, like so many, was already a fan of the series. Indeed, he greatly anticipated the chance to work with Reeves, and wasn’t disappointed by the experience.

“Not only was Keanu amazing to work with, he was genuinely lovely to be around,” enthuses Mantzoukas. “What amazed me is that he’s getting hammered day after day, yet he was still delightful and welcoming and generous to me.”

Generosity is a quality that Mantzoukas holds in high regard. It undoubtedly fuels his comedic philosophy, honed during his training as an improvisational actor. The American-born Greek actor was a member of the Upright Citizens Brigade Theatre (UCB), an improv training centre founded by Amy Poehler, Matt Besser, Ian Roberts and Matt Walsh. Alumni include Kate McKinnon, Zach Woods, Rob Coddry, Donald Glover, Ed Helms and Aziz Ansari, and Mantzoukas notes that his training helped him cultivate an attitude of support around comedy, rather than ego-driven competitiveness. He further notes how his improv background helped him on cult TV hit Brooklyn Nine-Nine, as well as The House, which featured Amy Poehler and Will Ferrell.

“It’s pretty generous, everybody’s very supportive,” he says of those sets. “Improv comedy is all about a philosophy of support and making sure everybody looks good. But it also comes down to the project, and the writing being good enough for everyone’s character to have a distinct point of view, so they’ll always get to do their jokes – no-one else can do their jokes. There has to be room for everybody so that everybody gets to score.”

The UCB alumni are dominating the comedy scene in the States right now, in the same way that The Groundlings – whose members included Will Ferrell, Kristen Wiig, Maya Rudolph and Conan O’Brien – dominated it for a good 15 years. Previous to that, it was Second City Chicago and Toronto who produced a lot of the original Saturday Night Live and National Lampoon cast members.

“Every generation has a theatre that defines their comedic point of view,” Mantzoukas agrees. “Now it’s UCB, probably because it happens to teach and produce a comedic skillset that’s currently in demand. Groundlings produced a lot of big character people who ended up on Mad TV or SNL, while UCB produces a lot more naturalistic performances. In the time of Seth Rogen and Judd Apatow, it’s not about big, Austin Powers-level characters. It’s about characters who are slightly more grounded in reality; that’s what UCB does well. But it’s all about trends.”

And the 46-year-old knows what it’s like not to be in comedy fashion. When Mantzoukas started in New York in the ’90s, improv and sketch comedy were not in vogue – New York was a stand-up city. He says he spent years performing to tiny audiences.

“That hustle and grind was hugely important though,” he reflects. “It showed us that even though we thought we were good, success wasn’t inevitable. Talent is just one part of a career. There are a lot of talented people who don’t figure it out and aren’t successful, because there are all these other components that you have to figure out. Work ethic, tenacity, drive, ambition – all of these things have to coalesce into something that makes you keep going. Some of the funniest people I did comedy with in New York don’t do it anymore. They were like, ‘I don’t want to do this for another six years without a break. I don’t want to go to auditions every day for jobs I don’t get. I have a family and kids, I want security and less stress, and I don’t have another five years to just see if this works.’ And they’re successful at other jobs now. Sometimes you see people who are not the most naturally talented, but they might be the most tenacious.”

It’s his appreciation for effort and guts that makes Mantzoukas appreciate a big fail as much as a big win. He co-hosts the podcast How Did This Get Made, which examines and deconstructs awful films. Victims have included the infamously terrible The Room, Xanadu, Glitter, The Wicker Man, and several instalments of the Twilight and The Fast And The Furious franchises. “It’s not about trashing anything or taking anything down,” says Mantzoukas. “More often than not, we’re celebrating them! Like, when we talk about The Fast And Furious movies – I love them. But the first movie is about guys doing street racing and stealing combination TV/VCRs, and in the last movie, they’re driving cars against a submarine on the frozen ice – it’s crazy what’s going on. So our approach is celebrating silly movies, which is much more fun than just trashing something. Part of the podcast is about watching a movie and knowing why it doesn’t work. And then there are films like The Room that are bananas on a different level. Watching Tommy Wiseau making insane choice after insane choice is pretty magical.”

Mantzoukas’ loving mockery of The Room actually led to a small role in James Franco’s The Disaster Artist. “It’s really funny and as a fan of the movie, I was just frankly excited to be part of it.”

And did he meet Tommy Wiseau?

“I did – when the movie screened at SXSW, Tommy and Greg Sestero were both there, which was just beyond exciting. He is as intense as you’d expect. What a dream.”

• John Wick: Chapter 3 – Parabellum is in cinemas now.