Behemoths are the most powerful super mutants by far, towering above any player character, at about 13 feet (4 m) tall. These super mutants are the oldest and strongest of their kind and are many times larger than any other humanoid creature, almost as large as a mirelurk queen. Unlike regular super mutants, they will not speak; instead, they will make monstrous roars.

They are often armed with incredibly large melee weapons such as a fire hydrant mounted on a large pipe. They also have the ability to throw heavy boulders at their enemies. Either way, both weapons are heavy hitters and will cause major damage against any enemy smaller than them. They carry a cage made from shopping carts on their back, which they use to carry boulders that they use during combat.