David Duchovny and Rosemarie DeWitt play cousins who are completely and utterly awful people in the new black comedy “The Estate.”

But then, every major character in “The Estate,” which also stars Toni Collette, Anna Faris and Kathleen Turner, is just as terrible. And that, DeWitt and Duchovny say, is what made it so much fun to make.

“It was super fun and rewarding,” DeWitt says. “And weirdly, it’s not a lot of work upfront because the characters don’t change. They start out awful and they stay awful.

“So you get to tap into all these parts of yourself, like revenge fantasy,” she says. “Anything you have that you don’t like about yourself, you get to put it all into the character.”

Duchovny agreed, saying it felt invigorating in a strange way to play a character with no limits — for better or worse (and almost always worse).

“I think to play a character who’s unapologetic is a gift,” Duchovny says. “In real life, and in dramas, we spend our lives apologizing for the things that we want, that we’re either ashamed of, or afraid to say out loud.

“You get a character like Richard who just says those things out loud and says them without any kind of sense that it’s embarrassing or humiliating or wrong,” he says. “And it’s kind of like having a superpower, you know, being on set like that.”

In “The Estate,” Kathleen Turner plays Aunt Hilda, a very wealthy, very mean, very lonely woman. When news that she’s dying surfaces, her nephew and nieces race to her mansion on St. Charles Avenue in New Orleans to ingratiate themselves to her, and hopefully, into her will.

Toni Collette and Anna Faris play sisters Macey and Savanna, who see Aunt Hilda’s estate as a chance to save the family diner in a worn-down neighborhood across town. DeWitt plays Beatrice, a woman whose smile hides a desperate willingness to do anything to get Hilda’s money.

Duchovny is Richard, though he announces he now prefers Dick, who while dim in almost every way has had the foresight to stay in touch with Aunt Hilda via phone calls and texts, and is in the lead to grab the estate as long as he doesn’t mess things up.

Spoiler alert: All of them mess things up in terrible, ridiculous, awful, and hilarious ways.

Many in the cast — which includes Ron Livingston, DeWitt’s real-life husband, as her hapless movie husband James — had worked with each other in the past.

Duchovny had cast Kathleen Turner in his Showtime series “Californication.” DeWitt co-starred with Toni Collette in the same network’s “United States of Tara.”

Duchovny had worked with Collette in the 2004 comedy “Connie and Carla,” but he and DeWitt had never collaborated, and some, such as Keyla Monterroso Mejia who plays Ellen, the younger half-sister of Macey and Savanna, were new to everyone.

“I don’t know, chemistry just isn’t an issue for me,” DeWitt says of how the cast quickly came together during the month on location in New Orleans. “It’s just a really generous experience when everybody kind of comes in. It almost feels like summer camp, or repertory theater or something where everyone just rolls up their sleeves and goes, ‘We don’t have a lot of time, we’re just gonna do this.’

“Rather than like, let’s say, like a huge budget comedy where people are really invested in how funny they are,” she says. “Or the jokes landing. It’s sort of the opposite. It’s literally like vaudeville or something in the best way.”

For Duchovny, the different backgrounds or performance styles of the cast blended together like disparate ingredients into a memorable gumbo.

“I think that for me, making a movie like this with these very different kinds of performers, all of them are good,” he says. “And everybody has their own kind of milieu and their own kind of vibe that they bring to the scene, or you know, their own kind of brand of comedy that they bring to the scene.

“I really love that discovery of, ‘OK, here’s a new person that I haven’t worked with,’” Duchovny says. “Here’s Rosemarie and we’re doing a scene. I’m gonna get to know her comedically right now, and this is cool. And now we’re trying to throw the ball back and forth together, you know, even though maybe we don’t work exactly the same way.

“Keyla, exactly the same way,” Duchovny says. “Like, weirdo stuff coming at me. Like, Oh my God, that’s off the wall. But I love that. It’s just cool to see everybody’s freak flag in this comedic sense. You know, like, they get to fly it a little bit because you’re making a comedy, and you’re just going for it.”

In a story where everyone makes wildly inappropriate choices, DeWitt as Beatrice probably makes the worst. Duchovny as Dick repeatedly tries to hook up with Collette’s Macey — not good, Dick! — but Beatrice asks her husband James to seduce dying Aunt Hilda, and honestly, it’s hard to top that.

“That part was really fun,” DeWitt says of being able to play a fictional married couple with her real-life husband. “The stage of life that we’re at, family dictates everything. And it’s not my tiny violin, but women, we turn a lot of roles down, work, to be moms, dad’s out of town.

“So it was a great package deal to say how about we bring the whole family to New Orleans for a month and have them go to school there for a month,” she says. That was the easy sell, I think, for Ron. He’s also a really big supporter and fan of mine. Like he wants me to be happy. He wants to show up and have that role be funny and me doing it funny.”