The Ancient Civilization was a race of magically and technologically adept beings that destroyed themselves by overuse of Nightmare Fuel, causing the periods of magical flux and possibly unleashing Shadow Creatures which helped in bringing their downfall. The Ruins are the remnants of their civilization.
Appearance of the Ancient Civilization race strongly resemble that of a Terrorbeak: overall body structure and spinal spikes visible on statues in Atrium biome and on obelisk's carvings can also be easily spotted on Terrorbeaks. Ancients' forked tails resemble the small legs of a Terrorbeak as well.
- The Ancients seem to have used electrical power in some form, as their Relics can drop Frazzled Wires when destroyed.
- While little can be confirmed about their appearance, the appearance of the Mage Statue reveals that the ancients may have been arthropodic in structure, with a slightly knobbly shell on their backs resembling that of a pill bug. It may be important to note that in the Nightmare Cycle, spikes can be seen extending from both the Head and Mage Statues, showing that they may have been able to extend spikes from their bodies maybe if angered or in self-defense.