Chicken Little is a Summon that appears in Kingdom Hearts II. He is obtained by talking to Merlin after visiting The Land of Dragons and Beast's Castle (or Olympus Coliseum if Sora skipped either of the aforementioned worlds). To summon him, Sora uses the Baseball Charm he receives from Merlin.
Chicken Little sets two firsts for a Kingdom Hearts character; he is the first character from a computer animated Disney movie to appear in the series, and he debuted in Kingdom Hearts II before his own movie debuted in Japan. Chicken Little's inclusion in Kingdom Hearts II has been seen as a way to promote his titular film in Japan, as the film was not yet released in Japan at the time of the game's Japanese release.
Chicken Little is a useful summon for defense and utility. He whistles occasionally to stun enemies and attract them to Sora, similar to Magnet, allowing groups of enemies to be handled easier. In terms of healing, Chicken Little can restore 40% of Sora's HP and Sora also regains a small amount of HP with every successful Keyblade hit. Chicken Little also fires baseballs to damage enemies. This is mimicked in his limit, FPS Mode, in which balls and firecrackers are fired at enemies.
Ace "Chicken Little" Cluck is the main protagonist of the 2005 Disney animated film of the same name, itself based on a popular folktale.
In the film, after he sees a hexagon-shaped object with an image of the sky fall from the sky, Chicken Little believes that the sky itself is falling and tries to warn the town, but in doing so he throws the town into a panic, leading him to be a laughingstock. A year later, he is hit by a similar object, and he and his outcast friends discover that it is a piece of an alien spaceship. A misunderstanding stemming from a lost alien child leads to an invasion of the town, leaving Chicken Little and his friends to return the alien and stop the invasion.