The Cat is the audience's favorite character in "Cinderella," the fairy tale spectacle that American Ballet Theatre danced and mimed at the Kennedy Center for seven performances, from Wednesday through last night. Perhaps the Prince and Cinderella get the most applause at the end of a performance, but they take their curtain calls together. It is the Cat that steals scenes and that the kids will remember next year when it's time to buy tickets again or, perchance, turn on the tube.

Michael Langlois and Gil Boggs, who alternate in the role, are cats of somewhat different concept. Langlois is more mellow. The wise way in which he cocks his head suggests an old philosopher. It might well be that he's the only philosopher in all of ballet. Pleasures, like curling up in the laundry basket or being stroked, he consumes with relish. Last year, on New Year's Eve, he took the liberty of catching a Bluebird from the Spring divertissement and gobbled her up like a true Epicurean. This ad lib should have been kept.

Boggs is always daring. He'll grow up to be a Puss-in-Boots, the sort of cat about whom a whole ballet could be built. Watching him dance with Cinderella, one wishes the Fairy Godmother would change him into the Prince.

There was a brand new Prince and a new-to-Washington Cinderella in Saturday afternoon's cast. Johan Renvall's debut as the hero was one of the few chances this season to see this fine classicist in a major dance role. The Prince doesn't appear until Act 2, and when he does it is from an unexpected direction. This entrance is one of the ballet's best jokes. Once on stage, the Prince is overlooked by his court. Because Renvall was short compared with his honor guard, their initial neglect of him became quite plausible. His subsequent gruffness with his officers was not just mean but also funny because they towered over him. The scale of Renvall's dancing and deportment is far from small. His extraordinary clarity of movement was undiminished, though he seemed a little less pliant than heretofore. In the Prince's variations, there is a deliberate asymmetry for the working leg. Renvall's penchant for perfect equilibrium actually diminished this interesting eccentricity.

Cheryl Yeager's Cinderella was one of her freshest performances in some time. She is a dancer who can make a change of speed or direction look like a delicious surprise. Her characterization, more than that of other interpreters of the role, showed a girl resigned to the lot of the drudge but one who bore no grudges. The acting was simple yet sure. Cynthia Gregory, Saturday night's Cinderella, played the part as if she were in scenes from realist plays. In the scullery, she is so harried that not only her steprelatives but even the viewers overlook her beauty. At the ball, she drips so much glamor that one wonders about her innocence. The Cinderella story is too slender a line on which to hang a lot of wet laundry. What made Gregory's performance worthwhile was the power of the dancing. The footwork could be lightning fast. Balances were developed slowly, luxuriously. She streamlined movement in ways other dancers, especially of her height, seldom risk.

Ross Stretton, Gregory's Prince, is more the standard tall dancer. He cuts a commanding figure on stage, but is at greater ease in steps that travel than in movement about a center. He's a very deft partner. Carla Stallings' gentle Fairy Godmother and Deirdre Carberry's pert Springtime were noteworthy on Saturday evening. At the matinee, Peter Fonseca was new as the masochistic Step-Sister and Scott Schlexer was all nerves as the Step-Mother. Alan Barker conducted both performances. Boggs was the afternoon's Cat and Langlois the evening's.