|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.
An improved form of the Behemoth type called Ballistra was introduced after the original unit was destroyed. These units were submersible and carried more firepower and armor then the original. These units were used in the assault on Mithril's West Pacific Fleet base. These units used large auxiliary propulsion units mounted on the back resembling 2 submarines connected to each other.
The red Behemoth operated by the terrorist group A21 ws the first to be seen on active engagement. While the manufacturer is unknown, the Behemoth was designed by Amalgam. After destroying an M9E Gernsback piloted by Melissa Mao, a Japanese Self Defense Force unit from Naroshino equipped with the Type 96 used rifles and cannons against it, but its Lambda Driver prevented any damage, and the Japanese Self Defense Force unit was taken out. Kurz Weber disabled its fixed weapons, and it was destroyed when the cooling apparatus for its Lambda Driver was shot by Sousuke Sagara's ARX-7 Arbalest, causing it to shut down and 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: 42 meters
- Weight: Approx. 1500 Tonnes
- Power Source: 3x Gas Turbine Engine with 12000 Kw each
- Maximum Operation Time: 40 Hours
- Top Speed: 30 knots (on the sea)
- Maximum Jump: 5 meter unassisted
- 4 x 30mm machine guns
- massive AS sword
- 300mm howitzer cannon
- many x missile batteries (located atop on the shoulders)