Dark Gaia was an entity that featured in Sonic Unleashed.
The history of the Dark Gaia would forever be inscribed on the scrolls within the Gaia Manuscripts which explained the fate of the world before when the entity was unleashed as part of its periodic cycles.
It had a massive serpentine body that was linked to the planet itself with six clawed arms stretching from its body once its final form was attained. The creatures head resembled that of a hammerhead which served as a type of mouth with many teeth but also held its many eyes. A single large eye was in the centre of this orifice and Dark Gaia was capable of firing a powerful energy beam at its enemies from it. It was also capable of releasing tentacles from its main body that speared up and generated a shield around its main body. Harming the tentacles ultimately brought down the energy barrier.
Though a monstrous looking creature that embodied the darkness, Dark Gaia represented part of the balance that engulfed the world as it was the counterpart of Light Gaia.