Michelle Triola Marvin, a former nightclub singer whose claims as the one-time live-in girlfriend of actor Lee Marvin led to a landmark ruling that established the legal concept of palimony, has died. She was 75.

Ms. Marvin, who had fought lung cancer for 18 months, died Friday at the Malibu, Calif., home she shared with actor Dick Van Dyke, her companion of 30 years, said a family friend, Bob Palmer.

Michelle Marvin, who legally changed her surname to Lee Marvin's even though they never married, made legal history in 1976 when the California Supreme Court ruled that she and other unmarried persons could sue for property division when a relationship ends.

That decision paved the way three years later for an often sensational, 11-week trial, in which Michelle Marvin was awarded $104,000 for what the judge called "rehabilitative purposes."

Both sides declared victory, but Michelle Marvin perhaps won best sound bite: "If a man wants to leave his toothbrush at my house, he better bloody well marry me," she said after the 1979 trial.

An appeals court later blocked her from collecting the money, but the legal principle underlying her court battle was left intact. "Palimony" became a dictionary entry and grounds for a slew of cases involving celebrities and their former cohabiting lovers.

The so-called Marvin decision underscored the extent to which the sexual revolution of the 1960s had changed American society.

Michelle Marvin was born in Los Angeles on Nov. 13, 1933, and majored in theater arts at the University of California, Los Angeles. According to Mr. Palmer, she gained notice as a singer in the 1950s when she performed at a club on the Sunset Strip owned by Jerry Lewis. She also danced in the 1958 Broadway production of "Flower Drum Song" directed by Gene Kelly.

She met Lee Marvin in 1964 when she had a bit part in the movie "Ship of Fools." They began dating and within a few months Mr. Marvin left his wife and began staying at Michelle's Hollywood apartment. In January 1965 they moved into a house he found for them in Malibu.

Later, she testified that Lee Marvin, who won an Academy Award for best actor in "Cat Ballou" during their relationship, had asked her to give up her career and that he would take care of her.

In May 1970 she legally added Marvin to her name but the next month the actor had her evicted from the Malibu house. He married his childhood sweetheart, Pamela Feeley, in October of that year. In November 1971 he cut off a monthly allowance he had been paying to Michelle.

In February 1972, she took him to court.

With her attorney, the flamboyant Marvin Mitchelson, she calculated that her former boyfriend had earned $3.6 million during the six years of their cohabitation. She sued for half of that sum, $1.8 million. Mr. Mitchelson, who was a famous celebrity divorce lawyer, said he intended to "put marriage on trial" in the Marvin case.

The Los Angeles Superior Court trial was a tabloid dream. Both Marvins took the stand, providing numerous moments of high drama. He said he never loved her; she said he proposed marriage twice. He said she threatened suicide; she said he made her pregnant three times and paid for an abortion. (One pregnancy ended in miscarriage, and two were terminated.)

In the end, Superior Court Judge Arthur K. Marshall denied her $1.8 million claim, ruling that there was neither an express nor an implicit contract obligating the actor to share his wealth with her.

He awarded her $104,000, a sum equivalent to her highest weekly salary for two years. He said the money was "rehabilitative," intended to pay for training, "so that she may return from her status as a companion of a motion picture star to a separate, independent ... existence."

Michelle Marvin found the concept of "rehabilitation" demeaning but said she felt she had "accomplished something really wonderful."

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