Thena is a member of the genetically-engineered Eternals. Created by the Celestials in the World Forge, Thena was sent to Earth in 5000 BC alongside others nine Eternals to help progress the planet's societal development, and protect it from the Deviants, with the time becoming in a legendary warrior and even in a greek legend. However, in 1521, while fighting the last Deviants in Tenochtitlan, Thena's Mahd Wy'ry causes her to momentarily turn on her allies, only to be stopped by Gilgamesh. The Prime Eternal, Ajak, offers to cure Thena's affliction at the cost of her memories, but Gilgamesh volunteers to look over her, becoming her de-facto partner in the exile.
In 2023, Thena was living with Gilgamesh in exile in Australia, when their fellow Eternals arrived to reform the team to stop the Emergence. Thena continued to suffer from her Mahd Wy'ry, and it was soon revealed it was caused by her previous memories from other worlds, as she subconsciously knew Earth was doomed. Thena agreed to help the others stop the Emergence. After Gilgamesh was killed by him, she developed a hatred for the Deviant Kro and sought to take revenge. During the battle against the traitorous Ikaris, Thena faced off against and killed Kro, avenging Gilgamesh. After they prevented the Emergence, Thena, alongside Druig and Makkari, journeyed into space on the Domo in search of other Eternals. In space, they encountered the Eternal Starfox.
