Brittany Murphy, the perpetually perky and slightly quirky actress who worked her way up from supporting parts to romantic leads after her breakout role in the film “Clueless,” died Sunday in Los Angeles. She was 32.

Ed Winter, an assistant chief coroner in Los Angeles County, told The Associated Press that Ms. Murphy apparently collapsed in the bathroom and that the cause of death “appears to be natural.” He said that an official cause of death might not be determined for some time.

The Los Angeles Fire Department responded to a call at 8 a.m. Sunday at the home that Ms. Murphy shared with her husband, Simon Monjack, a British screenwriter, in West Hollywood. Ms. Murphy was taken to Cedars-Sinai Medical Center, where she was pronounced dead at 10:04 a.m. Sunday, said Sally Stewart, a spokeswoman for the hospital.

The actress’s wide brown eyes and unrestrained, asymmetrical smile made her a frequent choice for the role of ditz with an edge — such as the urban transplant to a Beverly Hills high school in “Clueless” and the riches-to-rags au pair in “Uptown Girls” — or a woman over the edge, playing characters with severe mental illness in the thriller “Don’t Say a Word” and the drama “Girl, Interrupted.”

The 1995 teen comedy “Clueless,” an adaptation of Jane Austen’s “Emma” set in southern California and starringAlicia Silverstone, was a surprise hit, and though Ms. Murphy was 17 when she played the supporting role of Tai, the airhead persona stuck with her. It was her 2003 stint as the romantic lead in the Eminem vehicle “8 Mile,” she told The A.P., that earned her more recognition.

“That changed a lot,” she said in the 2003 interview. “That was the difference between people knowing my first and last name as opposed to not.”

Peter Travers of Rolling Stone said Ms. Murphy played the character of Alex “with hot desperation and calloused vulnerability. She’s dynamite.” But she was never a critics’ darling. Stephen Holden of The New York Times was among those who compared her unfavorably to other female contemporaries, writing that she “suggests a dumbed-down Meg Ryan with a gloss of Melanie Griffith” in the 2004 romantic comedy “Little Black Book.”

Ms. Murphy was born on Nov. 10, 1977, in Atlanta. Her parents divorced when she was very young, and her mother, Sharon, raised her primarily in New Jersey before bringing Ms. Murphy to Los Angeles to pursue a screen career.

But during the filming of “Clueless,” her mother was diagnosed with breast cancer, an event Ms. Murphy said affected her profoundly.

When Sharon Murphy’s cancer returned in 2003, Ms. Murphy told People magazine that she “went to every doctor’s appointment and chemo session” with her mother. “My mom taught me there’s always a way to channel your fears into love.”

A diverse set of credits accumulated in Ms. Murphy’s filmography, including the tough, abused waitress in the gritty “Sin City,” a concentration camp victim in the television film“The Devil’s Arithmetic,” and the voice of an animated penguin in “Happy Feet.”

She also lent her voice to the character Luann on more the 200 episodes of Fox’s animated series “King of the Hill,” and collaborated on a song with the D.J. Paul Oakenfold.

“I don’t really take myself very seriously,” Ms. Murphy told The San Jose Mercury News in 2003. “I’ve never formally trained in acting, so I’m very instinctual and visceral with decisions. It hasn’t really been a plot or scheme in any way, shape or form.”

Indeed, her image often slipped beyond her control. She was repeatedly romantically linked to her co-stars, including Ashton Kutcher from “Just Married,” and a string of broken engagements made her tabloid fodder.

Ms. Murphy married Mr. Monjack in 2007. She is survived by him; her mother; her father, Angelo Bertolotti of Branford, Fla.; and a brother.

The Sylvester Stallone film “The Expendables,” which features Ms. Murphy, is in post-production and is scheduled to be released next year.

Brittany A Bertolotti