When Marvel Comics. Before Loki proved his heroism, he seemingly died after being the cause of Asgard’s destruction, forcing them to take refuge on Earth. Loki returned as a child and put villainy behind him, as he went up against the Devourer of Worlds, Galactus, himself.
In Odin knew it contained the power to create an entirely new reality. However, the Galactus Seed being pulled into the physical world alerted Galactus to its power, and the Devourer of Worlds sought to take it from Odin. Galactus believed that if he consumed the Worldheart, he would no longer be perpetually hungry and could stop feeding on entire planets. Odin did not want to give Galactus the Seed, no matter how many trillions of lives it could have saved, and so the Asgardians prepared for war.
Odin and his army led by Thor met Galactus and the Silver Surfer in space above Earth to vanquish the world killer once and for all. The Asgardians put up a valiant fight, with Odin famously headbutting Galactus in the face during the battle as well, but it was all futile as Galactus is a force of nature that is not easily destroyed. During the battle, Loki remained on Asgard because he wanted to be rid of the Worldheart before Thor got himself killed fending off Galactus. Loki stole the Seed and returned it to the split World Tree, throwing it into the pit of light and energy so that it could never be found again. With the Galactus Seed gone, the Devourer of Worlds went back to his planet-consuming ways and the war with Asgard was finished.
While Loki saved Thor’s life along with all of what remained of Asgard from the cosmic powers of Galactus, he was still met with hatred and distrust. Loki knew that no matter what he did, no one would ever love him because of how villainous he was in the past. Even though he would not be recognized for his heroic actions, Loki still defeated Galactus and saved Thor simply because he felt the overwhelming need to do so.
While Loki didn’t outright defeat Galactus in an epic space battle as Odin tried to do, he did defeat the Devourer of Worlds by removing the artifact that had the nearly unstoppable force of Galactus from the path of Thor and the rest of Asgard. Loki used his wits to best a cosmically-powerful being not even Odin could beat, defeating him in true Loki fashion. Loki finally became a hero by defeating Galactus where Odin couldn’t, though the tragedy of the situation is that even this great example of heroism couldn't Loki.
