Mokele Mubenbe

Mokele Mubenbe, also known as the One That Stops the Waters or The Lernaean Hydra by humans, is an ancient reptilian creature.

Appearance
It is a massive beast with a long neck, spear like horns, pillarlike legs, a tail, fangs, and a fan of plates sprouting from the back of the neck and down its back. Its body, thicker than a wall, is covered in tough skin. Overall, it resembles a sauropod dinosaur.

Background
Mokele Mubenbe is a reptilian beast that has lived for countless ages. Despite its great age, it is still considered young since it has yet to have more heads.

Goblin Slayer Volume 7
Mokele Mubenbe was brought under the control of a goblin shaman, allowing it to be ridden by goblins to rampage near the elf forest. It was eventually subdued by Goblin Slayer's party after all four of its legs were tied up and after Dwarf Shaman cast Stupor on it. When it fell unconscious, Mokele Mubenbe's body crushed the goblin riders who were still alive.