As one of Marvel Comics’ most powerful entities, Galactus can overwhelm even the gravest threat – including the near-omnipotent Celestials themselves. While these Celestials are some of the most dangerous beings in the Marvel Universe, many fans wrongly think Galactus doesn't stand a chance against them, when in fact the Devourer of Worlds is more inherently powerful than even several Celestials working together.
Galactus proved his mettle in Fantastic Four #602 by Jonathan Hickman and Barry Kitson, when Marvel’s First Family found themselves caught up in an interstellar war taking place between the Kree Empire, the Inhuman Royal Family, and even the Annihilation Wave led by a recently resurrected Human Torch. This battle threatened to tear the solar system apart, so Mr. Fantastic and the Invisible Woman summoned Galactus – who had already vowed to aid them at the end of all things – to intervene in the world-threatening cosmic conflict. Galactus arrives, agreeing to handle the Kree but warning that this is not the previously foretold threat for which he has consumed four worlds in preparation. The Kree continue their onslaught against Galactus, though their weapons are ineffectual against the Devourer of Worlds.
But the arrival of four mad Celestials from Earth-4280 stops all sides of the conflict in their tracks. A fully charged Galactus stands against their agenda of domination and destruction, and the Celestials recognize him as the threat he truly is. The Celestials swarm the Devourer, only to be met by an opponent equal to their power. Galactus manages to hold the beings off, even killing one of the four. The remaining three giants use the corpse of their comrade to merge into a more powerful combined form. This singular entity dispatches the Devourer of Worlds, blasting him with an intense burst of energy and seemingly killing him. In desperation, the Fantastic Four use a weapon known as Sol’s Hammer to separate the merged entity, but without Galactus, they’re still hopelessly outgunned. But just as all hope seems lost, an adult Franklin and Valeria Richards arrive from the future to turn the tide.
This reality-warping adult Franklin manages to defeat one of the remaining Celestials, but he too is outnumbered and overwhelmed by the enormity of their power. In a moment of crisis, Franklin uses his power to revive Galactus as his herald, gifting the Devourer the power he needs to rise again. This resurrected and empowered Galactus is more than a match for their cosmic foes. He even rips one of the Celestials in half with his bare hands.
While Galactus ultimately needed backup to handle the four merged Celestials, the beings were no match for the Devourer of Worlds individually, even all attacking at once. Killing two Celestials with his bare hands truly cements Galactus as the ultimate powerhouse of the Marvel Universe. The character has often been described as a force of nature, and this conflict goes to prove just how overwhelming the Power Cosmic can be. Galactus may need to power-up by consuming worlds, but this is a natural part of his biology, and it's clear that even without special preparation, he'd be more than capable of defeating a single Celestial unless he was already depleted.
The Celestials are grave threats on their own. They’ve threatened the Earth on more than one occasion, and in Uncanny Avengers #22, it took the combined powers of Earth's mightiest heroes to even slow Exitar the Celestial Executioner's descent toward Earth. With this year’s Eternals fully bringing the Celestials into the MCU, along with the inevitable introduction of the Fantastic Four and Galactus, it’s only a matter of time before fans get to see this cosmic conflict on the big screen.