Cheshire Cat

The Cheshire Cat is a pink and purple cat from Wonderland with the ability to teleport. He speaks in riddles and wears an almost permanent grin on his face.

Kingdom Hearts
In the first game, this cat aided Sora at first, but then turned against him by summoning the Trickmaster, which the cat called "Shadow". It was revealed in the Manga that the prank playing cat was working for Maleficent.

Chain of Memories
The Cheshire Cat appeared in here as one of Sora's Wonderland memories, giving him advice on how to save himself from being executed by the Queen of Hearts (albeit in riddles).

Quotes

 * "Shadows here, shadows there, shadows everywhere, and the mome raths outgrabe!"
 * "The shadows are coming! Are you prepared for the worst? If not, too bad!"