LOS ANGELES (Reuters) - Actress and dancer Cyd Charisse, the impossibly long-legged movie musical star who gained fame for her on-screen pairings with Hollywood dance greats Fred Astaire and Gene Kelly, died on Tuesday at age 86.

Charisse, a sinuous, athletic performer once described by Astaire as "beautiful dynamite," died early in the morning of a heart attack at a Los Angeles-area hospital, according to her agent, Scott Stander.

Publicist Gene Schwam said she had only recently celebrated her 60th wedding anniversary with her second husband, singer Tony Martin, whom she married after a romance with millionaire Howard Hughes.

"What was special about Cyd was that she was always stylish and graceful, and when I saw her two weeks ago, she was still dressed beautifully and her hair was done properly," Schwam told Reuters. "She was such a loving and gracious woman throughout her life."

Born Tula Ellice Finklea in Amarillo, Texas, she took her professional surname from her first husband, ballet instructor Nico Charisse. The moniker of Cyd was adapted from a childhood nickname, Sid, coined by her brother.

Joining the Ballet Russe as a teenager in the mid-1930s, she broke into movies in 1943 dancing opposite Don Ameche in "Something to Shout About," billed then as Lily Norwood.

That appearance led to a long-term contract with Metro-Goldwyn-Mayer, where she first danced with Astaire in a brief routine in "Ziegfeld Follies" and made her film acting debut with Judy Garland in "The Harvey Girls," both released in 1946.

But Charisse cemented her status as an MGM star as Kelly's dance partner in their provocatively memorable "Broadway Melody Ballet" routine in the finale to the 1952 classic "Singin' in the Rain."

She co-starred with Kelly in 1954 in the Scottish-themed musical "Brigadoon" and again two years later in "It's Always Fair Weather."

Charisse also had been offered the female lead opposite Kelly in "An American in Paris," but lost that role to newcomer Leslie Caron when she became pregnant with her son, Tony Martin Jr.

Her collaborations with Astaire, whom she later saluted as "the most perfect gentleman I have ever known," also included the 1953 musical "The Band Wagon" and the 1957 classic "Silk Stockings," which earned her a Golden Globe nomination.

Astaire returned the compliment in his autobiography, writing of his partnership with Charisse: "That Cyd! When you've danced with her, you stay danced with."

But when asked whether she preferred dancing with Astaire or Kelly, Charisse cleverly demurred, answering, "It's like comparing apples and oranges. They're both delicious."

As the popularity of Hollywood musicals waned at the end of the 1950s, so too did Charisse's movie career.

But she later performed in nightclubs, often with Martin, and after years of working in summer stock stage musicals, she made her Broadway debut in 1991 in the musical "Grand Hotel," starring in the role originated in the 1932 film by Greta Garbo.