Behemoth

The Behemoth is a powerful Heartless which appears in Kingdom Hearts. It is based on Behemoths from the Final Fantasy series, large purple monsters with two bull-like horns and a lion-like body. It is one of three powerful Heartless released by the Final Keyhole, which is also the Keyhole to Hollow Bastion. The other two are Phantom and Kurt Zisa, who leave to attack Neverland and Agrabah while Behemoth remains and guards the keyhole.

Although the first Behemoth is found in Hollow Bastion, other Behemoths are found in the Olympus Coliseum and End of the World. These other Behemoths were repurposed as Destroyed and Arc Behemoths in Kingdom Hearts: Final Mix.

Journal Entry
''Immensely powerful Heartless. With their large frame, they trample enemies, and repel most attacks. Damaging their weak point makes them lose consciousness. Strike them with potent attacks while they are down.''

Destroyed Behemoth
In Kingdom Hearts: Final Mix, Sora battles the Destroyed Behemoth in the Hades Cup in the Olympus Coliseum. The Destroyed Behemoth is a slightly more powerful palette swap of the original Behemoth.

Arc Behemoth
In Kingdom Hearts: Final Mix, Sora battles Arc Behemoths at the End of the World. These are merely palette-swaps of the Behemoths fought there in the original game.

Strategy
Despite their menacing appearance, Behemoth can be defeated relatively easy, compared to many other bosses. His only weakness is the small black horn on his head, which is more often than not out of the player's reach while standing on the ground. The trick is to jump on to the thigh of one of his hind legs and then further on to his back (or just directly onto his back, if possible), and then simply run up to the back of the horn to avoid falling of due to Behemoth's head movements. From this position, one can attack freely, and without the possibility of being attacked by Behemoth. Also, ice, thunder, and fire magic doesn't affect him.

Trivia

 * All three types of Behemoth are not actually considered Boss-level Heartless, according to the Journal, in which they are placed with other normal Heartless like the Wizard and Invisible.
 * Two Final Mix-version Behemoths are seen during the Battle of 1000 Heartless, but were not actually included in the battle.