The Behemoth is an Emblem Heartless that is found in Kingdom Hearts and Kingdom Hearts Re:coded. It is found in Hollow Bastion, End of the World and the 40th seed of the Hades Cup in Kingdom Hearts and is a boss in Olympus Coliseum's Layer 25 in Re:coded.
The Behemoth is one of the three powerful Heartless released by the Final Keyhole. The other two leave to attack Neverland and Agrabah, while Behemoth remains and guards the Keyhole. Other Behemoths are also found in the Hades Cup and End of the World. These Behemoths were repurposed as the Destroyed and Arc Behemoths in Kingdom Hearts Final Mix.
Kingdom Hearts Re:coded
A Behemoth is a massive, quadrupedal Heartless. Its body is predominantly lilac in color, but its back and all four of its legs are violet. Each of the Behemoth's legs have two toes with black claws. It has two large, curved tusks sprouting from its lower jaw that are white on their upper half and lilac on their lower half. The Behemoth's conical, black horn is on its forehead. Like most other Heartless, it has yellow eyes and a jagged maw. Its Heartless emblem is on its chest.
It is based on Behemoths from the Final Fantasy series, large purple monsters with two bull-like horns and a lion-like body.
Despite its menacing appearance, the Behemoth can be defeated relatively easily, compared to many other bosses. Its only weakness is the small black horn on its head, which is more often than not out of Sora's reach while standing on the ground. The trick is to jump on to the thigh of one of its hind legs and then further on to its back (or just directly onto its back, if possible), and then simply run up to the back of the horn to avoid falling off due to Behemoth's head movements. From this position, one can attack freely, preferably using Ars Arcanum.
If Sora attacks the horn enough, the Behemoth will temporarily fall to the ground making it easier for the whole party to fight it. However, once it recovers consciousness, it will attack with a wide spread thunder like maneuver. Precise timing is needed to evade this attack at close range with Dodge Roll. Behemoth may also very occasionally leap from one place to another.
Blizzard, Thunder, and Fire magic doesn't affect it. Also, when the Behemoth charges up its energy ball rain attack (an orange ball will start glowing in between his horns) get under its back legs and stay there until the balls stop raining and then make a dash for the weak horn.
If Sora cannot make it to the Behemoth's horn, a possible alternate strategy is to use any form of Gravity magic. Since the Behemoth is slow, it will almost always be hit, and given its high HP, it will quickly lose a lot of HP. This also depletes Sora's MP quickly however.
The prize for defeating the Behemoth in Hollow Bastion and the one in End of the World is the Omega Arts accessory. Another appears in the Hades Cup, where victory over it earns you the Blizzaga upgrade, and a fourth appears in the area just prior to the Final Rest save point in End of the World.