The Little Card has the ability to shrink anything, including one's magical power. Its main body is just like the one depicted on its card: a tiny girl child with blonde hair in a yellow jester's outfit. The Little's true form has also been shown to be very nimble and able to jump great heights for its size (not like The Jump, though). It is under The Light and is the sister card to The Big.
The Little first appears in Episode 24. Little had shrunk Sakura to the card spirit's size and her magic, so she could not use any Clow Cards. Sakura chased The Little all around the first floor of her house, stopping The Little from shrinking Touya as well. Then The Little jumped up the stairs to Sakura's room, but she could follow as she could not use any of the Clow Cards. Cerberus then helps Sakura get to her room where she literally runs into The Little and reverts to her normal size, finally sealing the card.
The Little was used by Sakura to make Kero small enough to enjoy a small piece of cake.
The Little was transformed in Episode 55 along with The Big. Sakura was trapped in the story of Alice in Wonderland, where the characters were represented by people she knew, due to another spell by Eriol. She had tried to use both The Big and The Little to her advantage, but it didn't work out.