Glenn Howerton on his new show ‘Sirens’ — and why he likes playing ‘raving lunatics and maniacs’

He’s going from the D.E.N.N.I.S. system to the beach.  

Glenn Howerton, best known for starring in “It’s Always Sunny in Philadelphia,” co-stars in the new Netflix miniseries “Sirens” (premiering May 22). 

“I had never read anything quite like this script, tonally. It’s like a suspenseful drama, but it’s also really funny,” Howerton, 49, exclusively told The Post. 

The plot follows Devon (Meghann Fahy, “The White Lotus”), who thinks her sister, Simone (Milly Alcock, “House of the Dragon”) needs to be rescued from her new job. Simone has been working for the wealthy socialite Michaela Kell (Julianne Moore) who Devon thinks is running a cult at her lavish beach estate. 

Kevin Bacon co-stars as Michaelas’s husband Peter, and Howerton plays their friend and Simone’s boyfriend, Ethan. 

“[Ethan is] so different from so many characters I play,” Howerton explained. “[But] he has an element of other characters I play. He’s not a slob. He’s a well put together rich dude, which is a little bit typecasting for me.”

Ethan isn’t fundamentally a bad person, despite being, “a bit naive and oblivious at times,” the actor continued. “I’m always getting cast as raving lunatics and maniacs, so it’s nice to do something different, every once in a while.”

Howerton has previously appeared on “The Mindy Project,” “Fargo,” and “Blackberry,” and has played sociopathic Dennis Reynolds on “It’s Always Sunny” since its 2005 debut.

“I do think a lot of actors enjoy playing things that are very different from themselves, and having the opportunity to – as Dennis would put it – wear another man’s skin,” he quipped. 

“For me, there’s something cathartic about portraying characters that behave in a way that I would never behave. And getting to just be selfish and narcissistic and a bit of a jerk and just yell at people,” Howerton continued.

“I strive to be a good person in my real life, so it’s fun to be bad. And I find them funny and sad and sort of pathetic — narcissists — and people that walk into the world not thinking about how their actions impact other people. I think it’s a bit sad and definitely frustrating. So I like to send it up in a satirical way.”

Since Howerton is 49 and Alcock is 25, their “Sirens” characters are in an age-gap romance. 

“That’s just what it is in the story, so I approached that situation the way I would approach any similar situation, regardless of the person’s age – with a lot of communication and respect on set, to make sure we’re all on the same page with how we shoot the scenes,” he explained. 

“Milly is just a consummate professional, it was a lot of fun.”

As for his other co-star, Julianne Moore, he gushed: “She’s so cool.”

“I think she’s aware enough of her status within the business to want to put people at ease, as quickly as possible. She’s possibly had experiences in the past where people were maybe intimidated to be around her, because she plays such powerful characters often, and she has such a powerful glowing presence.”

It would be “easy” to be intimidated by her, “but she knocks those things down pretty quickly and is just a very grounded and wonderful person and a lot of fun to hang out with between scenes,” he concluded. “She’s not just there to be a giant movie star, she’s a real artist.”