There's big a HUGE debate about this on another board. I originally believed that Galactus was the highest expression of physical might in the universe, being the bridge between the physical universe and the abstract beings that exist beyond our ability to comprehend. But after really, truly reviewing all of G's appearances, I don't know how I came to that conclusion.
Celestials have routinely shown themselves to operate on a completely different level of power. They're basically the Q of the Marvel Universe, able to manipulate reality itself on a whim. Galactus, on the other hand, seems to be a massive energy battery and discharger. Like some kind of Cosmic Uber Cyclops.
Celestial wins. Easily.
Galactus was once manipulated by the dreaming celestial one of the greatest if not the greatest celestial ever he made galactus's hunger go through the roof he was even gonna have Galactus eat the celestial home world but in the end the dreaming celestial was the one who was eaten so no one celestial vs galactus would be dinner for galactus.
like someone mentioned early isnt big G suppose to be the last sole survivor of a race thats one with the universe. if he dies doesnt the universe? if its a guy like eternity then big G would lose but against some others he would win.
thats the problem with marvel at times. they make these super powered characters and then, they downgrade them. then anyone has a chance of beating them. Remember how powerful big G was in his earlier apperances or what about magneto. now almost anyone cant beat them or fight them 2 a draw. when galactus can easily wipe them out with a blink of an eye
I have a Thor comic where a celestial comes to this planet that Thor ends up on and he does nothing but monitor the planet and it's inhabitants.
Then Exitar shows up and dwarfs that "judgement" celestial but like 4x his height. Everyone on the planet tries to escape because they fear that Exitar will destroy the planet. When Exitar lands, he incases the entire planet in a force field so no one can get out.
At the end of the comic, after Thor has forced his way into Exitar's brain, Thor finds out that Exitar has eliminated all of the bad people on the planet leaving only the good people...and he fixes the environment of the otherwise dead planet.
I'd say he has significant reality warping skills if he can a.) destroy only the bad people b.) turn a nearly desert planet into a utopia.
Galactcus could probably take down a couple of celestials before he died. Personally, I think he'd lose to Exitar one on one.