Icthultu was a bloodthirsty god, referred to as an "old one."
Apparently, Icthultu was once worshiped by the people of Thanagar, until their culture rejected him, as well as religion outright, having gotten tired of his constant demand for sacrifice.
Thousands of years later, Icthultu was preparing for his return. Doctor Fate, Aquaman and Solomon Grundy began a ritual to hinder his efforts, but the Justice League's interference disrupted the ceremony, allowing Icthultu to temporarily materialize. Fate and Hawkgirl managed to seal the rift, preventing Icthultu from entering Earth. With little choice, the Justice League went to Icthultu's dimension to stop him.
Icthultu was apparently destroyed by the joint efforts of Hawkgirl and Solomon Grundy.
- Icthultu's name, appearance, and title as an "Old One" is based on H. P. Lovecraft's character, Cthulhu.