Stealth Sneak

Stealth Sneak (ステルススニーク) is an Emblem Heartless that appears in Kingdom Hearts. It is one of the bosses at Deep Jungle.

Kingdom Hearts
''Heartless that attuned to the darkness in Clayton's heart. It somehow manipulated the light to turn invisible and fought alongside Clayton.''

Kingdom Hearts
In Kingdom Hearts, the Stealth Sneak was attracted to the darkness in Clayton's heart, and used him as a puppet to help it defeat Sora, Donald, Goofy and Tarzan. However, the heroes prevailed, resulting in the death of both Stealth Sneak and Clayton, as it toppled on to him and crushed him to death.

Kingdom Hearts
In its first appearance, you will be facing the Stealth Sneak with Clayton as its rider. It is best if you focus on attacking this creature first, depleting its first HP meter to render it visible. The Stealth Sneak then acts a lot like Sabor. Continuously attacking it and using Fire spells will do lots of damage. During the first part of the battle, you can also use Thunder spells to strike at both Clayton and the Stealth Sneak simultaneously. Three of these creatures appear later during the Hades Cup, but without riders and with a new dark-gray coloring. If you attack the Stealth Sneak long enough, it will buck and Clayton will be sent flying. Clayton will seek higher ground when he is dismounted. He has a short amount of life and will use a potion often when it hits critical, but keep in mind that just like you Clayton has a limited amount of potions.

It has two main attacks, a lunge and a "spell" of sorts. The lunge can be dodged by Dodge Roll. When visible, the attack can be seen by the stance it takes before lunging, but when invisible, the best way to "see it coming" is by locking on to it, since the stance involves it lowering the head, which is the thing that Sora locks on to. So when the Lock-on ring suddenly lowers, dodge. Its other attack can be seen either way. Its hands start glowing and it will extend them, and when it brings them together, the attack launches. Simply time a jump with the movements of its arms.

After Clayton is thrown off, try and focus most of Sora's attacks against him. When Clayton is defeated, so will Stealth Sneak. You do not have to kill Stealth Sneak before defeating Clayton.

Trivia

 * There seems to be some confusion on how the Stealth Sneak killed Clayton. When the Disney villains are discussing it, Oogie says he "got chomped", and indeed, if one looks closely, it does appear Clayton got crushed in the Sneak's open jaws as it fell on top of him. The cutscene is not clear enough to make out all the details though. However, it is evident that Clayton lost his heart to darkness, as he disappeared with the Stealth Sneak after being defeated.
 * The Stealth Sneak bears a strong resemblance to a chameleon that Simba roared at in The Lion King just before the Wildebeest Stampede.