Thena is a member of the Eternals, a genetically superior offshoot race of humanity who possess abilities such as levitation and immortality. She is known for being a fierce warrior and for having amorous relationships with a great multitude of men over the centuries. Thena's most consistent recurring relationship is a forbidden one with the warlord known as Kro, who is a member of the Eternals' arch-enemy race, the Deviants. Thena held the highest title of Prime Eternal for a time, but later stepped down from this position to give it over to Ikaris.