|First appearance||Behemoth Awakening|
The Behemoth is unlike any conventional Arm Slave in both its sheer size and its design. The Behemoth relies on a Lambda Driver to offset the gravimetric stress caused by the mass of its own body. Otherwise, it would collapse due to its own weight. The Lambda Driver needs to be continuously active while the Behemoth is mobile. This places a lot of stress on the pilot who needs to concentrate on both combat and maintaining sufficient power levels in the Lambda Driver.
The unit was developed as an AS hunter, its armaments, size and defense capabilities make it one of the most dangerous AS designed by Amalgam.
The red Behemoth operated by the terrorist group A21 is the first to be shown on active engagement. While the macnufacturer is unknown, the Behemoth has was designed by Amalgam. This Behemoth is destroyed when the cooling apparatus for its Lambda Driver are shot by Sousuke Sagara's ARX-7 Arbalest, causing it to shut down and the Behemoth to collapse.
In the course of the novels, at least 6 more are used in engagements, 3 on the attack at Merida Island and 3 more on the attack of Leonard Testarossa hide out in Mexico
- Crew: 1
- Height: 40 meters
- Weight: Approx. 1500 Tonnes
- Power Source: Gas Turbine Engine
- Maximum Operation Time: 40 Hours
- Top Speed: 30 knots (on the sea)
- 4 x 30mm machine guns
- massive AS sword
- 300mm howitzer cannon
- many x missile batteries (located atop on the shoulders)