Loretta Swit, who won two Emmy Awards playing Major Margaret Houlihan, the demanding head nurse of a behind-the-lines surgical unit during the Korean War on the pioneering hit TV series M.A.S.H., has died. She was 87.

Publicist Harlan Boll says Swit died Friday at her home in New York City, likely from natural causes.

Swit and Alan Alda were the longest-serving cast members on M.A.S.H., which was based on Robert Altman’s 1970 film, which was itself based on a novel by Richard Hooker, the pseudonym of H. Richard Hornberger.

The CBS show aired for 11 years from 1972 to 1983, revolving around life at the 4077th Mobile Army Surgical Hospital, which gave the show its name.

The two-and-a-half-hour finale on February 28, 1983, lured over 100 million viewers, the most-watched episode of any scripted series ever.

Rolling Stone magazine put M.A.S.H. at No. 25 of the best TV shows of all time, while Time Out put it at No. 34. It won the Impact Award at the 2009 TV Land annual awards.

It won a Peabody Award in 1975 “for the depth of its humor and the manner in which comedy is used to lift the spirit and, as well, to offer a profound statement on the nature of war.”

Swit transforms the character of Houlihan

In Altman’s 1970 film, Houlihan was a one-dimensional character — a prickly, rules-bound head nurse who was regularly tormented by male colleagues, who gave her the nickname “Hot Lips.”

Her intimate moments were broadcast to the entire camp after somebody planted a microphone under her bed.

Sally Kellerman played Houlihan in the movie version and Swit took it over for TV, eventually deepening and creating her into a much fuller character.

Her sexuality was played down and she wasn’t even called “Hot Lips” in the later years.

The growing awareness of feminism in the ’70s spurred Houlihan’s transformation from caricature to real person, but a lot of the change was due to Swit’s influence on the scriptwriters.

“Around the second or third year I decided to try to play her as a real person, in an intelligent fashion, even if it meant hurting the jokes,” Swit told Suzy Kalter, author of “The Complete Book of M.A.S.H.”

“To oversimplify it, I took each traumatic change that happened in her life and kept it. I didn’t go into the next episode as if it were a different character in a different play.

“She was a character in constant flux; she never stopped developing.”

M.A.S.H. wasn’t an instant hit. It finished its first season in 46th place, out of 75 network TV series, but it nabbed nine Emmy nominations.

It was rewarded with a better time slot for its sophomore season, paired on Saturday nights with All in the Family, then TV’s highest-rated show.

At the 1974 Emmys, it was crowned best comedy, with Alda winning as best comedy actor.

The series also survived despite cast churn. In addition to Swit and Alda, the first season featured Wayne Rogers, McLean Stevenson, Larry Linville and Gary Burghoff.

Harry Morgan, Mike Farrell and David Ogden Stiers would later be added, while Jamie Farr and William Christopher had expanded roles.

“Loretta Swit’s portrayal of Margaret ‘Hot Lips’ Houlihan was groundbreaking — bringing heart, humor, and strength to one of television comedy’s most enduring roles.

Her talent extended well beyond that iconic character, with acclaimed work on both stage and screen that showcased her intelligence, versatility, and passion,” National Comedy Center Executive Director Journey Gunderson said in a statement.

Swit appeared in all but 11 episodes of the series, nearly four times longer than the Korean War itself, exploring issues like PTSD, sexism and racism. Swit pushed for a better representation for women.

“One of the things I liked, with Loretta’s prodding, was every time I had a chance to write for her character, we’d get away from the Hot Lips angle and find out more about who Margaret was. She became more of a real person,” Alda told The Hollywood Reporter in 2018.

The series ended on a happy note for Houlihan, who spends much of the finale debating whether she wants to head to Tokyo or Belgium for her next overseas post.

Ultimately, she opts to return to America and work at a hospital, citing her father — a career Army man.

Swit didn’t personally agree that was the correct decision for a military-minded official: “I didn’t think that was correct for my Margaret,” she told Yahoo Entertainment in 2023.

“I think her next move was Vietnam. So I didn’t agree with that, but that’s what they wanted her to do.”

But the actor did get to write the speech that Houlihan delivers to her fellow nurses on their final night together, in which she says: “It’s been an honour and privilege to have worked with you. And I’m very, very proud to have known you.”

“I was consumed with writing that. And I still get letters from women all over the world who became nurses because of Margaret Houlihan.

To have contributed to someone’s life like that is remarkable,” she told Yahoo Entertainment.

During her run, Houlihan had an affair with Hawkeye’s foil, the bumbling Frank Burns, played by Linville in the TV version, and in Season 5, Houlihan returns from a stay in Tokyo engaged to a handsome lieutenant colonel, a storyline that Swit says she advocated for with the writers.

“I told them: ‘Can you imagine what fun you’re going to have with Larry when I come back to town and I tell him I’m engaged? He’ll rip the doors off of the mess tent!’ And that’s exactly what they had him do. So we were all of the same mind.”

Toward the end, Swit was tempted to leave the show.

She played the role of Chris Cagney in a 1981 television movie, Cagney & Lacey, and was offered the part when it was picked up as a midseason series for the spring of 1982.

But producers insisted she stay with M.A.S.H. for its last two seasons.

Swit told The Florida Times-Union in 2010 she might have stayed with M.A.S.H. anyway. “You can’t help but get better as an actor working with scripts like that,” she said.

“If you’re in something that literate, well, we got spoiled.”

In 2022, James Poniewozik, The New York Times’s chief television critic, looked back on the show and said it held up well: “Its blend of madcap comedy and pitch-dark drama — the laughs amplifying the serious stakes, and vice versa — is recognizable in today’s dramedies, from ‘Better Things’ to ‘Barry,’ that work in the DMZ between laughter and sadness.”

After the TV series, Swit became a vocal animal welfare activist, selling SwitHeart perfume and her memoir through her official website, with proceeds benefiting various animal-related nonprofit groups.

In 1983, she married actor Dennis Holahan, whom she’d met when he was a guest star on M.A.S.H. They divorced in 1995.

Swit was born in New Jersey

Born in Passaic, New Jersey, the daughter of Polish immigrants, Swit enrolled in the American Academy of Dramatic Arts, then paid her dues for years in touring productions.

In 1969, she arrived in Hollywood and was soon seen in series such as Gunsmoke, Hawaii Five-O, Mission Impossible and Bonanza.

Then in 1972, she got her big break when she was asked to audition for the role of “Hot Lips.”

She would regularly return to theater, starring on Broadway in 1975 in “Same Time, Next Year” and “The Mystery of Edwin Drood” in 1986.

She was in “Amorous Crossing,” a romantic comedy, at Alhambra Theatre & Dining in 2010 and in North Carolina Theatre’s production of “Mame” in 2003.