The Atlanteans were an ancient race of humanoid beings that ruled the Earth before humanity. They contracted a disease from space, however, and so went into hibernation until a cure could be discovered.
Originally they were identical to humans, however disease caused the race's flesh to deteriorate and melt, making them look horrific.
Many years ago, the people of Atlantis created a seemingly perfect society, all that changed when a meteor struck and the denizens were infected by the bacteria within it. Creating the mechanical creature Uzahra to put the survivors in stasis until a cure could be found.
When Uzahra was reactivated during the battle between the Getter Robo G and the Oni brothers, three Atlanteans appeared out of Uzahra after it destroyed the Hyakki Beasts and attacked the Getter. Curious as to why the still conscious Ryoma Nagare was still fighting in spite of a hopeless battle, they decided to take the Getter Team on board and prepared to transfer their brains into the Getter Team's bodies. The Getter Team was prepared to damage their bodies to make sure it didn't happen until assassins from the Hyakki Empire interfered destroying most of the in-stasis Atlanteans. The Getter Team managed to get free and fight off the assassins. The dying Atlanteans then gave the Getter Team Uzahra to use against the Hyakki Empire for revenge.
- It's never clearly stated when the Atlanteans ruled, but its probable that it was sometime after the Dinosaur Empire was the ruling force on Earth.