Diane Cilento, the dusky-voiced stage and film actress whose forthright sensuality was best displayed as the wench Molly in “Tom Jones” and who endured a tempestuous marriage to actor Sean Connery, died Oct. 6 in Queensland, Australia. She was 78.

Australian media outlets reported the death but did not reveal a cause.

The Australian-born Ms. Cilento was a rising star in the 1950s and 1960s — a wide-eyed, striking blonde with a beckoning, throaty voice that she proudly said was “an octave lower than Paul Robeson’s.”

On Broadway, she made a strong impression as Helen of Troy in Jean Giraudoux’s “Tiger at the Gates” (1955) opposite Michael Redgrave. Writing in the New York Herald-Tribune, theater critic Walter Kerr said Ms. Cilento’s Helen was a “marvel of insolence.”

“With her antennae-like eyelashes sweeping nations into the dustbin,” he wrote, “her one dainty hoof pawing the ground before her impatiently, and her detached nasal voice slicing reason into ribbons, she is a creature from the moon — a terrifying one.”

Ms. Cilento gained wider exposure in leading British film and television dramas. On TV, she played Eugene O’Neill’s waterfront tramp in “Anna Christie” (1957) opposite her future husband, Connery. That same year, she appeared as a ladies’ maid opposite butler Kenneth More in “Paradise Lagoon,” based on J.M. Barrie’s play “The Admirable Crichton.” The oft-told story was about a shipwreck that tears down class boundaries.

Ms. Cilento was perhaps best remembered for her Oscar-nominated role as the unquenchably lusty Molly, the voluptuous daughter of a gameskeeper, in “Tom Jones” (1963). Tony Richardson’s bawdy version of the Henry Fielding novel starred Albert Finney as a dashing rake.

Ms. Cilento went on to co-star as the sexually assertive noblewoman Contessina de’Medici opposite Charlton Heston’s Michelangelo in “The Agony and the Ecstasy” (1965); a none-too mournful widow in the brutal western “Hombre” (1967) opposite Paul Newman; and as a teacher with a dark secret in “The Wicker Man” (1973), an eerie mystery about a missing girl and a Scottish paganist cult.

A minor film at the time of its release, “The Wicker Man” found a devoted following over the years. The journal Cinefantastique once called it “the Citizen Kane of horror films.” The screenplay was by the celebrated playwright Anthony Shaffer (“Sleuth”), whom Ms. Cilento married in 1985.

Diane Cilento was born Oct. 5, 1933, in Mooloolaba, Australia, to an eminent medical family and was educated in Brisbane. Her father, Raphael “Ray” Cilento, was a leading authority in tropical medicine. Her mother, Phyllis, was a gynecologist.

An interest in dance led Ms. Cilento to study ballet in New York. She later switched to acting and graduated from London’s Royal Academy of Dramatic Art before making her screen and professional stage debuts in the early 1950s.

By the time she met Connery in 1957 during the premiere of “Paradise Lagoon,” her first marriage to playboy-aristocrat Andrea Volpe had disintegrated.

She said she was “footloose and fancy-free, but pregnant by my Italian husband” when she saw Connery: “He walked with the forward-leaning, slightly pigeon-toed gait of a body builder, and his thick eyebrows met between his eyes. He looked dangerous, but fun.”

They wed in 1962 just as he was on the cusp of greater fame after playing James Bond in “Dr. No.” In her 2006 memoir, “My Nine Lives,” she offered a brutal portrait of their marriage, describing him as a jealous misogynist who was psychologically and often physically threatening. She said he grew angry at her independent spirit when she would not give up her career to support his.

She also accused him of beating her during the marriage. Connery issued a denial and said his comments in 1965 to Playboy magazine that hitting a woman was justified under certain conditions were taken out of context.

After their messy divorce in the early 1970s, Ms. Cilento returned to Australia and spent a period exploring mysticism and other forms of spirituality. She founded an open-air theater in far north Queensland, the Karnak Playhouse.

Her third husband, Shaffer, died in 2001. Survivors include a daughter from her first marriage, Giovanna Volpe; and a son from her second marriage, actor Jason Connery.

Before her memoir appeared, Ms. Cilento said she was often asked what it was like to be wed to Connery, considered one of the sexiest men alive.

“One of my favorite memories is when Sean and I were living in a house in London, where we’d been burgled 17 times,” she told an Australian newspaper in 2004. “It was after the incredible success of ‘Dr. No’ and the James Bond thing. One morning, Sean heard someone trying to steal his car. He jumped out of bed and chased him down the road naked. Even now, when I think of his bare bottom jiggling up the road, it makes me laugh.”