Beyond the studios, Ms. Shearmur collected contemporary art and photography and amassed an enviable wardrobe. Five feet tall in high heels, she was considered one of the best-dressed women in Hollywood. She even had her T-shirts tailored.
Her ability to wrangle filmmakers, actors and studio executives in common purpose was cultivated in childhood, when she learned to share and compromise as one of a celebrated set of quadruplets. Allison was Baby C, the third of the Brecker Quads, who were born in 1963 in Manhattan to great news media fanfare.
Ms. Shearmur attended law school at the University of Southern California while also taking film classes. After getting her law degree, she was hired as an assistant at Columbia TriStar. From there she moved to a junior executive role at the Walt Disney Company, and by 1998 she had joined Universal Pictures as a senior vice president for production.
That year, Ms. Shearmur asked the filmmaker Tony Gilroy to help write a screenplay based on “The Bourne Identity,” Robert Ludlum’s best-selling 1980 spy thriller.
“It was a lackluster project” that was not generating much excitement in Hollywood, Mr. Gilroy said in an interview. He told Ms. Shearmur he was not interested, but she persisted, pushing him to commit two weeks to writing a script.
“She was so relentless,” he said. “She absolutely connived me into the two weeks.”
Two weeks, he said, turned into two years, and the project turned into a billion-dollar franchise for Universal.
Ms. Shearmur left Universal in 2004 for Paramount and, four years later, joined Lionsgate, where she produced the first two films in the “Hunger Games” series and served as an executive producer for the third and fourth installments.
She left the company in 2012 to become an independent producer. “However successful she was as a studio exec,” Mr. Shearmur said, “this was the moment in her career when she really blossomed.”
The first project she took on as a producer was the live-action “Cinderella,” directed by Kenneth Branagh and released in 2015.
The year before that release, Kathleen Kennedy, the president of Lucasfilm, asked her if she would help produce “Rogue One.” It was during her work on that production that Ms. Shearmur learned she had lung cancer.
“When you see the success of the movie and complications of its production and the triumph of its reception, those things are to her credit,” said Mr. Gilroy, who helped write the script. “It’s as much her movie as anyone else’s.”
“That she won’t be able to see her work is unbearably sad,” Ms. Kennedy said.
Allison Ivy Brecker was born on Oct. 23, 1963, to Rhoda and Martin Brecker. Her mother was a schoolteacher, her father a lawyer. Allison was born after her siblings Lisa and John but before her sister Jodi.
Ms. Shearmur attended the University of Pennsylvania, graduating in 1985, and then headed to the West Coast for law school.
She met Mr. Shearmur, a British film composer living in Los Angeles, in 2000 on a blind date. They married about a year later.
In addition to her husband, Ms. Shearmur is survived by her sisters, Lisa Hartstein and Jodi Kahn; her brother, John; her parents; and two children, Imogen, 15, and Anthony, 10.
Ms. Shearmur’s husband said that despite her cancer, she was working till the end. The day before she died, he said, Ms. Shearmur attended a meeting about visual effects for “Solo.” And on the day she died, while in the hospital emergency room, she asked her husband to bring a certain script for her to read. It had been written by her former assistant, and Ms. Shearmur wanted to help it find its way onto a screen.