The Celestials are immensely powerful beings, considered by some to be villains (confirmed as such in a few official works, where they have fought heroes and villains alike, they are greatly feared even by a being of Galactus' might - although in others Galactus has engaged and defeated them).
Worshiped as 'space gods' by many races, they may be benevolent by their own lights (unlikely as they often act robotic and rather malevolent, save perhaps to their creations, the Eternals), but they have absolutely no regard for the interests of anyone but themselves. They consider virtually all other beings 'germs' (much like the Monitors of DC multiverse), and destroy entire worlds and species if they think its necessary. Even the Watchers are not safe from their judgment.
Celestials are gigantic armor-clad humanoids. They are approximately 2,000 feet tall, some of them are even larger (such as Exitar, their executioner; usually 20,000 feet tall, he can seemingly increase his size at will, attaining planetary-level stature) : the otherworldly 'mad Celestials' can also merge with each other to create even larger and formidable forms.
The origins of the Celestials have always been vague, but the First Firmament revealed they were already present in Its structure, and disturbed Its order. For this, they went to war with Its preferred creations, the Aspirants, and in the conflict the First Firmament was ripped apart. The Celestials then moved to the new multiverse which was formed out of its substance.
Some sources believe the Celestials actually created the first life forms in the nascent multiverse, as well as, eventually, beings which would introduce death. These destroyers were themselves deemed a failure by the Celestials and sealed away in a pocket reality.
The Celestials would come under attack by the Aspirants at least once during the previous - seventh - iteration of the multiverse, and many of them were slain by the Aspirants' hyperweapon, the Godkiller.
It is known that they have visited Earth on at least 4 occasions (known as Hosts) during which they would alter and exterminate many of Earth's natives. They created both the Eternal and Deviant offshoots of humanity, as well as altering humanity itself. They were also responsible for sinking Lemuria underneath the Ocean when the Deviants rebelled.
They have done this on many worlds throughout the universe, experimenting with life using entire planets as petrie dishes and mercilessly pruning the life forms they deem unworthy or useless. The ultimate goal of all this remains unknown. Nevertheless, they are not entirely deaf to placation; Thor and Susan Storm have both communicated with the Celestials.
The Celestials, along with many of the Marvel Universe's abstracts, are killed by the Beyonders when these beings mount their attack on the entire multiverse. They fight the enigmatic aliens with all their power, but are almost all destroyed. In the miniature universe created by God Doom in the aftermath of the multiverse's destruction, no Celestials exist per se, but the role of the moon is filled by an orbiting Celestial head called 'Knowhere'. It is stated that the head belonged to a being who attempted to invade Doomworld, but was slain by God Doom.
After the multiverse is re-created, it is revealed a small number of Celestials had managed to evade destruction by going into hiding; however they are located and destroyed by the Logos, who declares they are no longer needed in the new universal structure. The Logos turns out to have become corrupted by the First Firmament, who seemingly finally had its ultimate revenge on the rebels; but one single Celestial, the One Above All, finds refuge with the Never Queen, the embodiment of potentiality.
Notable Acts of Villainy
Although an amoral race of super-entities rather than true villains the Celestials have created dangerous artifacts and engaged in acts that some would consider immoral - usually to try and manipulate evolution in some fashion or to "purge" unwanted genetic codes from planets they are "progressing".
- creation of the Death Seed.
- creation of the Black Vortex, a device which realizes its users' ultimate potential; this led to the destruction of the race which it was given to
- Celestial technology is utilized by Apocalypse (though illegally so, since he was apparently punished by them over this over time)
- regular "purge" of worlds deemed "failures" of genetic manipulation (amounts to mass-genocide / planetary destruction)
- as a side-effect of a war between Celestials and the Godheads of Earth the Destroyer armor was forged.
- the creation of Terminus is a result of an act of vengeance by an alien race on the Celestials, who judged them "unfit" for existence.
- a group of Celestials encountered Galactus, who warned them he knew of their "true purpose" - this caused them to fly into a violent frenzy and try to destroy him, suggesting their true nature is sinister in nature.
- Reed Richards of the Fantastic Four fought Celestials and managed to harm them with his advanced weaponry, this is one of the rare moments the Celestials have shown any weakness (save against omnipotent enemies such as the Beyonders).
- the Celestials were said to have created the entire Deviant race just to consume en mass, they also mercilessly purged the Deviant race and destroyed much of their numbers - making the Deviants an endangered species.
- the Celestials have destroyed countless civilizations and worlds, putting their kill-count in the trillions.. even Galactus, himself a planet-consuming entity, views the Celestials as dangerous.
- they also created Mutants, thus in a sense the genetic war between humanity and these other "human variants" are part of the Celestials grand manipulation : they have also done similar manipulation across time and space, inspiring races such as the Kree and Skrull to do similar (a kind of "genetic arms-race" in which aliens create super-powered variants, often with cataclysmic results).
Powers and Abilities
the powers of the Celestials are for all intents and purposes limitless. When Odin, the head of one of Earth's most powerful pantheons, had decided to stand up to them. Working together with the heads of the other god families such as Zeus and Vishnu, he created a mighty weapon, the famous Asgardian Destroyer; when the Celestials reappeared on Earth, Odin animated the automaton with the life-force of all Asgardians except for Thor and confronted the space gods wielding the deadliest weapon in the world, the Odinsword. But the Celestials handily dealt with this ultimate attack as if it were a mere distraction.
- Ego ,who is actually an Elder of the Universe, appears as a Celestial in GOTG 2.