Galactus fights with MULTIVERSAL beings:

when Galactus gets out of control everybody has to gang up on him, even LT 

Galactus thrives on ALL forms of energy:

Galactus owned Abraxas:

Galactus operates on an omniversal level
 

 

  

 
 
 
 

 
 
 
 
 
 

 In the scan, Galactus is referring to an omniversal threat, and he is putting himself in Omniversal affairs. He is one of many beings that can operate across the Omniverse, not necessarily simultaneously, but he can venture out of the 616 multiverse. Galactus clearly balances the 616 Reality. What takes place in the 616 Reality impacts ALL of Marvel: (the Omniverse):

"The Marvel Universe is renowned for the presence of fantastic superhuman beings, the supernatural, and the cosmic. Although considered the “prime reality” in which events of universal significance occur (and, indeed, megauniversal and/or omniuniversal significance), this reality is designated as number 616 (thus, “Earth-616”) to differentiate it among the infinite numbers of alternate realities."

The 616 Reality seems to be the foundation of the Omniverse.
 
Galactus would be the balance of the Omniverse (all of Marvel). You see, Galactus was spawned from the Infinity Being. It was the only sentience in its Universe and everything was a part of him. There were no peers like Eternity/Infinity. Everthing that existed was the Infinity Being. It was in basic terms what Eternity/Infinity is, though on a much larger scale. Eternity and Infinity encompass everything in the Prime Multiverse, but they have others to assist them like Death, Galactus, Oblivion, the Living Tribunal, and so on, whereas the Infinity Being did not. So all other existence like Galan, like the rest of the realities there surely shared the Infinity Being's consciousness. That's why the dying Universe was still sentient and decided to bond to Galan to create a completely new reality (Current Marvel Universe). It was Galan's one universe that imploded and created the current Marvel Omniverse. The beginning of the Current Marvel Universe came from Galactus' Origin. (In Galactus' Origin the Previous entire universe implodes into a Cosmic Egg, just like the Infinity Being it was coincidentally sentient. If you tie in the canon existence of the Infinity Being, then Galan's Universe must have been a part of the previous Reality which was the Infinity Being. When the Infinity Being was dying it merged with Galan, where he continued on but was transformed into a new being called Galactus. And then, before dying, the Infinity Being put its consciousness into the Infinity Gems. An entirely new reality was created, the current Eternity who turned into a Multiverse. Then, time and space expanded further into sentient Megaverses, and then continued to expand beyond that into an Omniverse and is still expanding now.
 
 All this I got from on panel depictions/statements and 06'/07 bios.

There is more but you get the point, Galactus is a big player

He was also about to destroy Phoenix:

Galactus fought the inbetweener who was far above death:

Galactus can eat mephisto's realm:

Further proof of universe busting:

Annihilus plans to use Galactus as a power source to destroy both the positive - matter universe and the negative zone:    

Heals eternity:

Destroys elders of the universe:

Galactus can ressurect:

Here after they are in Death's realm, Death says that Galactus will reform if given enough time.


She can feel him reforming.


Strange will call on the Vishanti to help Galactus.


And, Galactus brings everyone back.


So... it was Galactus's own power that brought everyone back, but it was Strange that held off Death, and sped up the process.
So, basically, Galactus WOULD have done it himself, but Strange had made it go faster.
 

Galactus telepathy, beyond anything Thanos has encountered. That was after Galactus schooled, Moondragon and Thanos at the same time.

Galactus with UN can just erase from existence:

The UN which is a part of him. 
 

Heck all the heroes on earth can't phase galactus:

Galactus 616 which was previously in his natural state (a star of infinite energy), showed not only that he was the 1st and last galactus, but that he could make a fool of a multiversal threat (Abraxas):

Galactus' power can not be measured by thanos:

Doom with Galactus' power can do anything, (obviously he is not as strong as the beyonder):

I am pretty impressed by Galactus' feats, it sucks he is always the whipping boy when someone wants to show how powerful someone is...On a side note his action figure at Toys R Us was pretty awesome looking, I wanted to buy it for my son, but couldn't talk my wife into spending 60 bucks on a toy.

@ntb1124: yeah the marvel universe Galactus? its a realy cool figure.better than the other galactus released (The smaller one)

Galactus is not so powerful

Rom 27(casually transported an entire galaxy through time and space, with a mere thought)

Cosmic Powers Unlimited(Tyrant fight, casual galaxy busting once again)

Where ? Scan

Fantastic Four 339-341(Black Celestial Arc, he was eating entire universes, he ate a celestial)

Annihilation #6('herald my rage' blast which wiped out 9 solar systems, also Annihilus said that he had the power to destroy two universes)

not true he destroy three solar system no more

Infinity War(resurrected himself and his companions even though Death itself didn't want him to)

he was hit by a shot that could decimate a star system, but then the ship to regenerate not him

@ntb1124beta cuckold:

Brother..... silver surfer had like one infinitesimal amount of the power cosmic and he's killed a beyonder one shot and he's cool

@lord_oraculous016:

Is it nova, the herald of Galactus in that first pic

Taking 2 planets colliding while weakened is impressive:

Gallery

Or destroying 3 Solar Systems while weakened:

Gallery

The fact he can do/take these things while weakened makes him powerful and he's also the reason why i got into comics in the first place.