Photo: Jeffrey Mayer/WireImage

Mary Steenburgen is a sweetheart, and she often plays one — but not on Justified. In the FX drama’s final season, she’s Katherine Hale, a Kentucky crime boss’s vengeful widow who’s literally sleeping with the enemy, pot baron Avery Markham (Sam Elliott). “When I asked [executive producer] Graham Yost why he thought of me — since a lot of times, people only see me as playing nice people — he said, ‘Because I thought you could handle the humor of it,’” Steenburgen says. “I was honored, and I hope I’ve lived up to it.” The 61-year-old actress spoke with Vulture about joining Justified, New York in the ’70s, and her inability to stop herself from laughing on the set of Step Brothers.

Is it liberating for you to play a villain on Justified?

Katherine is fascinating to me. I actually felt I understood her very well from the get-go. She has her own bizarre morality. She wasn’t faithful to her husband sexually, but she’s faithful to him in terms of avenging his death.

Do you feel simpatico with Sam Elliott, with whom you previously co-starred in 2009’s Did You Hear About the Morgans?

Definitely. Sam and I just understand each other. I hadn’t seen him for a few years, but it was very easy for us to pick up. He’s still so willing to go out there and be on the edge. There’s not a been-there, done-that, phoning-it-in thing with him. He’s still very brave and interested, as am I. Well, I’m interested. I’ll leave it up to everyone else to decide if I’m brave, but I’m still very compelled by this work.

Is it bittersweet joining the show as it’s winding down?

Yes. I could have easily done a couple more years of this, although I’m doing multiple TV projects right now. I’m not sure my body would have been too happy about all the hours. But I was sad to say good-bye to everybody, and to my character. At the same time, it was a very heightened moment because every scene meant so much to everyone. So in a funny way, it was perfect for me.

As an Arkansan, how do you feel about the way Justified portrays the South?

I love that my character is southern and lethally intelligent. She might make immoral choices, but she’s really smart. I’ve had battles with writers who live in L.A. and were writing southern characters, because they felt like if they wrote “Sugar” and “Honey” at the end of every sentence, that would make it southern. There are no worse clichés than southern clichés. They make my skin crawl.

Have you always had an issue with Hollywood’s portrayal of the South?

I remember when I was growing up and watching southern people depicted on television, I thought, Well, based on what I’m seeing, I guess I’m supposed to be stupid and racist. It’s still, sadly, the easy route for a writer to go. These southern characters are far more diverse and complex than most.

You’ve also got roles in Orange Is the New Black, Will Forte’s Last Man on Earth, Robert Redford’s A Walk in the Woods, which recently debuted at Sundance, and with Anne Hathaway in Song One, which just opened in theaters and on VOD. Do you feel like you’re busier than ever?

This has definitely been one of the busiest times of my career, if not the busiest. I’m saying yes to more things because I have two children and two stepchildren, and there were a lot of times in my life when I felt like the timing was not right to work. Like all careers, mine has had ebbs and flows. I’m actually at an age when I didn’t expect to be working at all, but for some reason, it’s a very rich time for me.

You started out at the Neighborhood Playhouse in the early ’70s. What do you miss the most about the way New York City was in those days?

There was a really druggy, wild energy to New York then that’s very different now. The city wasn’t nearly as safe. I remember whole neighborhoods that I didn’t dare go to without a guy, and even then, I’d still be nervous. It’s a very different city now. Some people complain that it’s more boring and milquetoast, but I think it’s cool that kids today can own the whole island.

The two movies you made with Will Ferrell, Elf and Step Brothers, have become cult classics. Do fans often ask you about those films?

Step Brothers is probably the film the most people who approach me want to talk about. For years before that, it had been Back to the Future III. And Elf has become increasingly this film that families gather to watch as part of their Christmas ritual. So that’s really sweet.

How did you decide to work with Will again on Step Brothers?

He called me and said, “Would you be insulted if I asked you to play my mom — because I know you’re only 14 years older than me?” And I said, “Will, I would be insulted if you asked anybody else.” That job was like this reward for surviving the very difficult passages of my career. I felt like it was the business’s gift to me.

How so?

Because I’m kind of a laugh junkie. I really love funny people — I married a funny person [Ted Danson], my son [Charlie McDowell, director of last year’s indie comedy The One I Love] is a funny person. As Will Forte will now tell you, I’m incredibly undisciplined when it comes to getting the giggles. I’m the first person to break up. I really try. I’m not proud of it. There are so many shots in Step Brothers where you can see I’m laughing, and I said to [director] Adam McKay, “Why did you leave those takes in where you can see I’m laughing?” And he said, “Because, Mary, we have no takes where you’re not laughing.”