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.
By summoning Chicken Little, he can fire baseballs to attack the enemy. He also whistles occasionally to stun enemies and attract them to Sora, making damaging groups of enemies easier, and can heal 40% of Sora's HP by using his Healing ability. He's a particularly good summon for defense, as you can not be harmed while performing his limit. Sora also gains a small amount of HP every time he successfully hits an enemy with the Keyblade.
His Limit is FPS (First Person Shooter) Mode. In this mode, you can target the enemy through a scope and will have two abilities. One will throw firecrackers at the enemy, knocking them back and stopping them from moving; the other lets him throw baseballs to stun and damage the enemy. You can end the limit by pressing the Square button.
 See also