Phantom

The Phantom is a boss from Kingdom Hearts.

In brilliant contrast against the ominous glow of the Never Land clock tower, the battle against the Clock Tower Phantom is known as a sight to remember. The Phantom is one of the hidden bosses released by the Hollow Bastion keyhole to wreak destruction--they are some of the most powerful enemies in the game. However, the only one which's defeat is required to obtain everything in the game is the Clock Tower Phantom. Defeating it awards Sora with a Stop upgrade.

The Clock Tower Phantom haunts the clock tower until Sora is sent by Tinker Bell to stop it. It is unique in that if it defeats a party member, the member is sent to oblivion, where it cannot be revived until the end of the battle. The phantom utilizes the clock's hands to count down the vital seconds to a random party member's obliteration.

Other Appearances
Intriguingly, the Clock Tower Phantom may be seen as one of the ghosts in Fantasia, during the Night on Bald Mountain sequence. It rises out of one of the graves, sans the orb and Heartless emblem on its back.

Trivia

 * The Phantom failed to reappear in Kingdom Hearts: Final Mix. Instead, Xemnas acted as a hidden boss.