Shelley Duvall, the intrepid, Texas-born movie star whose wide-eyed, winsome presence was a mainstay in the films of Robert Altman and who co-starred in Stanley Kubrick’s “The Shining,” has died. She was 75.

Duvall died Thursday in her sleep at her home in Blanco, Texas, her longtime partner, Dan Gilroy, announced. The cause was complications of diabetes, said her friend, the publicist Gary Springer.

“My dear, sweet, wonderful life, partner, and friend left us last night,” Gilroy said in a statement. “Too much suffering lately, now she’s free. Fly away beautiful Shelley.”

Duvall was attending junior college in Texas when Altman’s crew members, preparing to film “Brewster McCloud,” encountered her as at a party in Houston in 1970. They introduced her to the director, who cast her “Brewster McCloud” and made her his protege.

Shelley Duvall poses for photographers at the 30th Cannes Film Festival in France, May 27, 1977. (Jean-Jacques Levy / The Associated Press)

Duvall would go on to appear in Altman films including “Thieves Like Us,” “Nashville, “Popeye,” “Three Women” and “McCabe & Ms. Miller.”

“He offers me … good roles,” Duvall told The New York Times in 1977. “None of them have been alike. He has a great confidence in me, and a trust and respect for me, and he doesn’t put any restrictions on me or intimidate me, and I love him. I remember the first advice he ever gave me: ‘Don’t take yourself seriously.’”

Duvall, gaunt and gawky, was no conventional Hollywood starlet. But she had a beguiling frank manner and exuded a singular naturalism. The film critic Pauline Kael called her the “female Buster Keaton.”

At her peak, Duvall was a regular star in some of the defining movies of the 1970s and 1980s. In “The Shining,” she played Wendy Torrance, who watches in horror as her husband, Jack (Jack Nicholson), goes crazy while their family is isolated in the Overlook Hotel. It was Duvall’s screaming face that made up half of the film’s most iconic image, along with Jack’s axe coming through the door.

But Duvall disappeared from movies almost as quickly as she arrived in them. By the 1990s, she began retiring from acting. Her last film role was in 2002’s “Manna From Heaven.” Duvall retreated from public life. Earlier this year she gave her first interview in years.

“How would you feel if people were really nice, and then, suddenly, on a dime” — she snapped her fingers — “they turn on you?” Duvall told the Times. “You would never believe it unless it happens to you. That’s why you get hurt, because you can’t really believe it’s true.”

This is a breaking news story. More details to come.