Known for her role as Angelique on the ABC soap opera Dark Shadows, on which she appeared from 1967 to its final episode in 1971, Parker worked on Hi, Mom during a production break. Having scripted lines to read on a daily soap opera, Parker was not accustomed to the improvisatory nature of De Palma's film. In a 2016 interview with Den of Geek's Tony Sokol, Parker said, "Brian De Palma cast me and they actually put in my two children. He was doing improvised theater. We were improvising on film, without lines, without a character to play. It was a whole different thing and I actually was not very good at it." Parker had a bathtub scene that De Palma had asked her to improvise, but it ended up being cut from the film. "I was very naive and not very courageous," Parker said in 2013. "He wanted me to improvise sexual fantasies ... in a bathtub … with bubbles … in the nude."

In an interview conducted after only the first day of filming, De Palma described the housewife character for Joseph Gelmis, in Gelmis' book, The Film Director as Superstar:

I got the idea for a housewife making a film diary of her life from David Holzman's Diary. She starts out with home movies. It gets more and more obsessive. She's very concerned with things. She has a scene where she talks about her body the way she talks about chairs and objects. Everything becomes an object for her.

Here's an excerpt from the Hollywood Reporter obituary by Mike Barnes:

Mere days after arriving in New York in 1967, the green-eyed Parker auditioned for Dark Shadows creator Dan Curtis, who cast her as Angelique in a story arc that would detail the origin of the tortured vampire Barnabas.

A soldier and the son of a shipping magnate, Barnabas in 1795 seduced and abandoned a servant girl from Martinique not realizing she was a witch. That girl was Angelique. “He just dallied with her and then dismissed her, and she was not to be dismissed,” Parker said in an undated interview for a Dark Shadows home video release.

An enraged Angelique would damn Barnabas to enteral life as a vampire, kicking off a battle between the two that would continue through different time periods.

“I played her as somebody who was much more of a tragic figure, who was desperately, desperately in love,” Parker said in 2016. “And her heart was broken. That’s much more sympathetic than just being a mean old witch. I felt that her acts were acts of desperation, not acts of evil.”

Though Angelique and others she would inhabit would perish, she would remain with the daytime serial through its April 1971 demise.

“Dan Curtis [would call Parker and say], ‘You’ve been great, kiddo, but we’re going to kill your character. Thanks a lot for everything,” she recalled in 2020. “Of course I was very sad, but about two months later they called me and said that they wanted me back.

“We were kind of the first team, and the fans seemed to watch it more when Angelique and Barnabas were fighting it out. That seemed to be the most popular part of the show, so [Curtis] brought me back many, many times.”

Parker was born Mary Lamar Rickey on Oct. 27, 1938, in Knoxville, Tennessee. Her father, Albert, was an attorney, and her mother, Ann, was active in civic groups.

She graduated from Central High School in Memphis and attended Vassar — she roomed with Jane Fonda there — and Rhodes College in Memphis, where at 19 she served as Wink Martindale’s assistant on his WHBQ-TV show, Dance Party. She then earned a master’s degree from the University of Iowa.

After a busy summer acting at the Millbrook Playhouse in Pennsylvania, Parker left her husband and two kids in Wisconsin for a spell to see if she could find work as an actor in New York. “By the time the children were 6 and 7 years old,” she said in a 1972 interview for Mid-South magazine, “I knew that I just couldn’t sit there and look at those fields for the rest of my life.”

In New York for her second-ever professional audition, she was cast as Angelique. “I think my only reaction to it was paralyzed fear,” she said.

Dark Shadows, which had debuted in June 1966, received a viewership jolt when Frid was introduced as Barnabas in April 1967. Parker arrived in the fictional town of Collinsport, Maine, seven months later.

“We realized [the show] was popular,” she said. “Everywhere we went [the cast was] recognized. There was a huge crowd outside the [Manhattan] studio when we finished in the afternoon of autograph seekers. People would show up, the same people every single day, day after day. They worshipped some of us and would walk us to the subway.

“I can remember standing on the subway when school got out and seeing 200 or 300 kids all waiting to take the train. They would see me and start screaming and run to the other end of the platform! They were so terrified because I was so evil.”

Meanwhile, feminists admired Parker because of her character’s strength, she said. “She was coming in at the beginning of the women’s movement and she was very independent,” Parker noted. “They sort of missed the fact that she was obsessed with her love for Barnabas and that was destroying her.”

On Facebook, her Dark Shadows co-star Kathryn Leigh Scott wrote Monday that Parker’s death left her “heartbroken, as all of us are who knew and loved her. She graced our lives with her beauty and talent, and we are all richer for having had her in our lives.”

During breaks in production, Parker acted on Broadway in September 1968 in Woman Is My Idea, which lasted just five performances, and in the early Brian De Palma film Hi, Mom! (1970), starring Robert De Niro.