Lynn Shelton, an indie filmmaker who helped popularize the mumblecore genre with works such as “Humpday” and “Your Sister’s Sister,” died Friday of a blood disorder.  She was 54.

Shelton was best known for her naturalistic, understated approach to comedy and drama in low-budget films that were hits with the Sundance crowd, but she reached a wider audience with her work on television, helming episodes of “The Mindy Project,” “Mad Men,” “Glow,” and “Fresh Off the Boat.” Recently, Shelton directed four episodes of the Hulu series “Little Fires Everywhere,” an adaptation of Celeste Ng’s 2017 bestseller that starred Reese Witherspoon and Kerry Washington.

Shelton began her career as an editor, later moving on to make experimental short films. She made her feature debut as a director with 2006’s “We Go Way Back,” the story of a 23-year old actress who is haunted by the specter of her thirteen-year-old self. It won awards at Slamdance, but was it was little seen for several years, gaining wider release after Shelton had become more established.

It was “Humpday,” with its provocative premise about two straight men who decide to make an amateur gay porn, that put Shelton on the map. The film was a buzzy breakout when it premiered at the Sundance Film Festival in 2009, winning a “Special Jury Prize for Spirit of Independence” and a distribution deal from Magnolia Pictures. Critics embraced the film, with Roger Ebert writing, “‘Humpday’ is funny, yes, but also observant and thought-provoking.”

Hollywood came calling, but Shelton largely steered clear of big movies, preferring to make quirkier, free-wheeling fare, though she was approached at one point about directing “Black Widow”.

“It’s very easy to have creative freedom when you’re making movies for a very small amount of money,” Shelton told Variety in a 2014 interview. “The more money involved, the more complicated it becomes because there are people involved who want to make sure they’re not throwing their cash down a big hole.”

Her improvisatory style arose at a time when other filmmakers such as Joe Swanberg and the Duplass brothers were making similar fare, and helped shape the DIY style of indie movies in the aughts. It was a movement made possible by advances in technology that gave aspiring directors access to cheaper digital cameras. Shelton’s other work included “Your Sister’s Sister,” a dramedy about an unusual love triangle between a grieving man, his best friend, and her lesbian sister, and “Sword of Trust,” a comedy about two sisters working to sell a family heirloom. Shelton wrote the screenplays for all of her films except for “Laggies,” an arrested development comedy that starred Keira Knightley and Sam Rockwell.

“I self-generated my work, and I never went around asking permission to make it,” Shelton told the Los Angeles Times in 2014. “The main reason women make inroads in independent film is that no one has to say, ‘I pick you.’ I’m not pounding on anybody’s door. I’m just making my own way. You can buy a camera for $1,500. It’s insane how easy it is to make a movie.

Shelton was born in Oberlin, Ohio and grew up in Seattle.  She attended Oberlin College in Ohio and then the University of Washington School of Drama, before moving to New York to enroll in the Master’s of Fine Arts program in photography and related media at the School of Visual Arts in Manhattan.

Shelton was married to the actor Kevin Seal. The couple had a son, Milo. Shelton was in a relationship with comedian Marc Maron at the time of her death.

Shelton is also survived by her parents Wendy & Alan Roedell and David “Mac” Shelton & Frauke Rynd. She is also survived by her brothers David Shelton, Robert Rynd and sister Tanya Rynd.