It is unknown how Stellaris survived the extermination of her home world by the Celestials or how she acquired her living armor, but ever since she has committed herself to their destruction. When the Celestials created a replicoid in the likeness of Thor, he was to serve as an ambassador for his mysterious masters. One such occasion was when the replicoid journeyed to Earth to summon Thor and Hercules to return to the Black Galaxy as commanded by the Celestials. The conversation between Thor and his twin counterpart was violently interrupted when Stellaris, the Celestial Slayer, attacked.
The initial assault, which destroyed a small part of the South Bronx, attracted the attention of the Avengers who intercepted her as she was preparing to assail Thor once again. Stellaris proved to be more than a match for the combined might of Captain America, Sersi, Quasar, Thor and She-Hulk, but the confrontation was halted by the repilcoid when he shouted a final command before Stellaris blasted him to oblivion. Stellaris left the scene, but detected another spawn of the Celestials to exact her revenge upon. Hercules, who had been a recent prisoner of the Celestials, was her next target, but thanks to the timely arrival of the Avengers, Stellaris would not claim a second life. Thor sensed that her power was similar to the power cosmic, so he chose himself to stand against her alone. The battle was fierce and both opponents were unwilling to yield, but the tide turned in Thor’s favor when he used his hammer, Mjolnir, to shatter the helmet of Stellaris. Thor was startled when it was revealed to be a woman inside the armor, and he momentarily stopped his attack. Stellaris threatened to destroy the planet when she activated her armor’s failsafe systems, so Captain America ordered her to be released. Stellaris left the planet only after reassuring Thor they would meet again when he traveled to the Black Galaxy.
Following Thor and Hercules, Stellaris soon found herself in New Wundagore, home of the High Evolutionary. She modified her armor to something stealthier and stowed away on his ship to find some new weapons she could use in her crusade against the Celestials. After disposing of a few guards, Stellaris freed the imprisoned Nobilus, one of the High Evolutionary’s New Immortals. Thor tried to stop the rampaging godling as Stellaris used her armor to tap into the ship’s computer system. Learning all she needed to, Stellaris grabbed Nobilus and exited the ship. She thought she now had an ally in her quest to eliminate the Celestials, but Nobilus was more concerned with his master’s wishes and obeyed his commands instead. As Nobilus and the other New Immortals contended with Thor, a new Celestial was about to be born, and Stellaris would not let this happen. She reconfigured her armor and attacked the Celestial where she thought it was most vulnerable, but the resulting explosion was the final catalyst necessary to allow this Celestial to be born.
It has yet to be revealed how she survived her encounter with the Celestials, but Stellaris returned, fully recovered, seeking revenge on Thor for abandoning her in the Black Galaxy. She tracked Eric Masterson, who was the new Thor, and engaged him in combat even as he was attacked by the Thor of the future, Dargo Ktor. She continued to fight both Thunder gods, but then decided to let them finish their battle since she could always get her revenge another time. Stellaris kept to the shadows, revenge far from her thoughts, as she followed Masterson, now Thunderstrike, secretly aiding him against such foes as Bloodaxe and the Juggernaut. She decided to reveal herself when she came to the aid of Thunderstrike and Spider-Man in a battle against S.H.I.E.L.D. and their Man-droid troopers, but left again soon afterwards. Surprising Masterson again at a later date, she had helped Thunderstrike against foes like the Absorbing Man and the Heliopolitan Death god, Seth. However, questions were raised about her mysterious powers when the Absorbing Man tried to soak up her powers and suffered a mental breakdown instead, so she headed for the stars once more in search of answers.
Stellaris recently turned up on the planet Godthab Omega after the Annihilation Wave started its path of destruction on the universe, and allied herself with Gamora becoming one of her Graces. She, and her ally Nebula, attempted to take on Ronan but were defeated by the superior power of his Universal Weapon. Stellaris was left badly injured and in need of medical treatment, and it can be assumed that she is still recovering from her recent battle with Ronan. Stellaris was still on Godthab Omega when the Wave invaded. It is unknown if she survived the assault.