Kelly died peacefully in his sleep at his Beverly Hills home on Friday. His third wife, Patricia, 36, whom he married six years ago, was at his side.
Kelly, who starred in On the Town, Singin' in the Rain, and An American in Paris, and spent a lifetime in films as a dancer, director and choreographer, had been ill after a series of strokes.
Frank Sinatra, who starred with Kelly in the 1945 film Anchors Aweigh, said yesterday: "Gene was a disciplinarian and a perfectionist - I should know. I practiced for hours and hours and couldn't believe it when I saw myself dancing with Gene on the big screen ... Gene was one of a kind. He revolutionised dancing in film."
"Hey, who else do you know who parlayed an umbrella and wet loafers into the greatest movie moment of all time," Bob Hope said in a tribute to his longtime friend, referring to Kelly's most famous film, Singin' in the Rain.
It was his solo performance in the 1952 film, in a scene which became a cinema classic where he danced and sang with an umbrella in a simulated downpour, that made the self-taught Irish-American dancer immortal.
The former ditch-digger and law school drop-out shone through the forties and fifties not only as a song-and-dance performer, but also as an innovative choreographer, and director. His joyful dancing, boyish good looks and regular-guy manner made him the perfect performer for postwar America.
Hope, a veteran entertainer, recalled that "his style, technique and innovation changed the world of dance in American films. What a talent. A dance instructor and a chorus boy with a degree in economics who gave more talent to the big screen than almost anyone I know."
Where Fred Astaire was polish, Kelly was muscle. Astaire danced in top hat and tails, Kelly in T-shirts and jeans.
"He once told me dancing was a man's game, as much of a sport as baseball itself," said Liza Minnelli, whose mother, Judy Garland, co-starred with Kelly in his 1942 film debut For Me and My Gal.
"And he made us believe that. He changed our minds and suddenly, all of America wanted to dance just like Gene Kelly," Minnelli said.