The Old Ones are extradimensional creatures, extremely varied in terms of physical form; ranging from misshapen shapes to others that resemble ocean creatures: kraken-like forms with toothed jaws and spiked tentacles, as well as others more reminiscent of fish, sea serpents or crustaceans. Their powers are magical in nature, allowing them to harm even Kryptonians.
In the past, the Old Ones visited numerous worlds in which they were worshiped as deities. The mightiest of the Old Ones was Ichthultu, who was worshiped as a god by primitive Thanagarians and gave them knowledge in many fields of science. However, the Thanagarians revolted against Ichthultu, tired of the sacrifices demanded by the Old One, who consumed the souls of his victims; and banished him from their world.
At the height of the Atlantean civilization, the Old Ones visited the Earth and posed a threat to Atlantis. King Poseidon forged his magical trident as a weapon powerful enough to seal the Old Ones back into their native realm, but at the cost of causing the entire city to sink beneath the waves.
- Justice League, s02e016, "The Terror Beyond", part 2 (2003)
- The Old Ones' appearance was based on the Great Old Ones from H. P. Lovecraft's works and his followers.