The original “Lost in Space,” which ran on CBS from 1965 to 1968, followed the interplanetary adventures of the Robinson family. On that series, Dr. Smith, as played by Jonathan Harris, was a conniving and campy foil who bickered with the family’s robot and spouted alliterative insults.
Matt Sazama and Burk Sharpless, the producers who developed the Netflix reboot, which began streaming last Friday, said that they did not want to copy or caricature what Mr. Harris did with the role.
Mr. Sazama and Mr. Sharpless reconceived the character, changing Dr. Smith’s gender and making her a low-level criminal on Earth, who steals her own sister’s identity — and later a doctor’s title and uniform — so she can reinvent her life in another star system.
Imagining their Dr. Smith as a 21st-century upgrade of the nefarious title character from “The Talented Mr. Ripley,” Mr. Sharpless said this approach was possible only because of Ms. Posey’s blend of comedic and dramatic talents.
“It wasn’t like we had the Dr. Smith you see on screen and then just went out and got Parker,” Mr. Sharpless said. “Parker allowed the Dr. Smith that you’re seeing to exist. She expanded the genre of the show.”
Ms. Posey has been a fan of “Lost in Space” since watching reruns during her childhood in Louisiana, “getting up at 5:30 in the morning to watch the static turn to color when the show came on at 6.”
She described her Dr. Smith as “a chameleon” who “survives by her wits,” which is not too different from how she has come to see herself.
During the last decade, Ms. Posey said, she has experienced a steep decline in the kinds of acting opportunities that best suit her. “I was like, I need to do something else — I need to express myself in a different way,” she said.
“When reality TV showed up, it was like, O.K., that’s it — game over, character actors, bye,” she said. “There are so many big chunks that are gone from the culture. It wouldn’t be that much of a turn to say, you know what? I’m going to become a landscaper.”
Over the years, Ms. Posey has occasionally dabbled in television, on shows like “The Good Wife” and “Search Party.” She said she also felt left behind by the explosion of serialized genre shows — like “Game of Thrones” and “The Walking Dead” — that she does not believe she would fit into and does not watch. (Even the Netflix sci-fi anthology “Black Mirror,” she said, is off the table: “I hear it’s really good, but I don’t want to watch it alone,” she explained. “I’m scared to.”)
Yet each time she’d speak to a friend or peer who was happily thriving in a genre TV role, she remained hopeful that an appropriate role would come her way.
Recalling a conversation she had had with Denis O’Hare, who was then playing a malevolent vampire on HBO’s “True Blood,” Ms. Posey said he told her, “It’s like Shakespeare — you get to be really epic in your emotions.”
Much to her satisfaction, “Lost in Space” has allowed Ms. Posey to perform her own Shakespearean pastiches, like a soliloquy addressed to the decapitated head of a robot. And it has let her share scenes with actors like Selma Blair (“Cruel Intentions,” “Legally Blonde”), a guest star who plays Dr. Smith’s wealthy, disapproving sister.
Describing a scene that required her to pass out (under the influence of drugs that Ms. Posey’s character had surreptitiously slipped her), Ms. Blair said: “I decided I was really going to milk it. And Parker was laughing, like, ‘I feel like you’re on an episode of ‘Columbo.’ You really love acting, don’t you?’ Coming from Parker, it wasn’t an insult.”
Ms. Blair said it was a positive development that Ms. Posey had finally made the crossover to serialized television.
“She should be a big-deal, household name,” Ms. Blair said. If TV hadn’t snapped Ms. Posey up already, she said it was because past series “might not be the best fit for people who have a real gravity and an eccentricity.” But now, Ms. Blair said, “They’re making such great shows for people like her, and hopefully one day for people like me.”