The Behemoth is a giant, quadrupedal Emblem Heartless that appears in Kingdom Hearts. It is a purple-and-lilac coloured, four-legged beast with a muscular body, two curved tusks jutting up from its lower jaw and a black horn atop its head. Sora and co. encounter this creature in Hollow Bastion after Sora's first battle against Ansem, then again in the End of the World.
The Behemoth is a slow, lumbering beast which is relatively easy to avoid, though its attacks are devastating when they hit. It walks around the area slowly, creating damaging shockwaves with each step. It can also leap into the air and create a massive shockwave upon landing that encompasses the entire floor. Its deadliest attacks, however, are Thundaga and Energy Rain; the Thundaga spell sends lightning bolts raining down all around the Behemoth which are almost impossible to dodge and the Energy Rain, when cast from the Behemoth's horn, sends energy balls raining down on the floor which explode on impact.
Sora cannot attack any part of the Behemoth's body except for the horn on its head. High Jump and Glide will be needed for Sora to get atop the monster's back and attack the horn. Once Sora is on its back, the Behemoth can do little to get him off and Sora will be free to attack the horn at will. The horn is only vulnerable to physical strikes and Arts; magic has no effect. After suffering enough hits, the Behemoth will become dazed and collapse, making it possible for the rest of the party to attack its horn until it gets up again.
- In Kingdom Hearts Final Mix, the Behemoths that appear in the End of the World and the Hades Cup at Olympus Coliseum are repurposed into the Arch Behemoth and Destroyed Behemoth respectively. These Behemoths have different colour palettes, but are otherwise the same as the standard Behemoth.
- The Behemoth Heartless is based on the Behemoth monsters that appear in the Final Fantasy games.