Cyd Charisse, the leggy beauty whose balletic grace made her a memorable partner for Fred Astaire and Gene Kelly in classic MGM musicals like "Singin' in the Rain," "The Band Wagon" and "Brigadoon," died on Tuesday in Los Angeles. She was believed to be 86.

Her death, at Cedars-Sinai Medical Center, was apparently caused by a heart attack, said her agent, Scott Stander.

Charisse came of age in a sparkling era of Hollywood musicals, and though she had some dramatic film roles, it was in musicals that she achieved her lasting renown. That fame later helped power a successful song-and-dance partnership with her husband, Tony Martin, in nightclubs and on television.

In his 1959 memoir, "Steps in Time," Astaire called Charisse "beautiful dynamite." She was a striking presence on film: slender and graceful with jet black hair. She stood 5 feet 6, but in high heels and full-length stockings — a familiar costume for her — she seemed even taller.

She made her film debut in 1943 under the name Lily Norwood in "Something to Shout About," with Don Ameche and Janet Blair, and then spent almost a decade performing in small roles and sometimes anonymously before she got her big break. That came with "Singin' in the Rain," released in 1952.

Written by Betty Comden and Adolph Green and directed by Gene Kelly and Stanley Donen, the film established her as one of Hollywood's most glamorous and seductive talents.

Set during the dawn of talking pictures, "Singin' in the Rain" starred Kelly, Donald O'Connor, Debbie Reynolds and Jean Hagen. Charisse appeared in only one of the movie's many indelible dance sequences, but one was enough. During the "Broadway Melody Ballet," opposite Kelly, she was both sultry vamp and diaphanous dream girl.

A year later, "The Band Wagon" brought Charisse her first leading role. Directed by Vincente Minnelli, with a book by Comden and Green and songs by Howard Dietz and Arthur Schwartz, the film starred Astaire, Charisse, Oscar Levant and Nanette Fabray.

Astaire played a fading Hollywood song-and-dance man hoping to make a comeback on Broadway who finds himself cast in a show opposite a snooty ballerina (Charisse). The couple do not see eye-to-eye until they take a nighttime carriage ride through a moonlit Central Park and wind up embracing languorously to the strains of "Dancing in the Dark."

One of the most famous sequences from the film, if not in the history of dance on film, is "The Girl Hunt Ballet," in which Charisse plays a sultry vamp to Astaire's private eye stage character.