CELESTIALS

The Celestials appear as silent, massively powerful humanoid armored forms with an average height of 2000 feet. Little is known regarding their appearance underneath the armor. Some believe it to only be a shell for beings of pure energy, so as to allow interaction with the physical world. It has been suggested that they may even be sentient stars. Their origin as their numbers remains a mystery as only a handful have ever been seen.

They travel the universe with an agenda of genetic engineering of younger species.

On Earth, they are apparentlt responsible for modifiying humanity in three offshoots, the Eternals, the Deviants and the Latents (representing most of the population), over a million years ago. The exact reason for the Celestials' genetic manipulation of proto-humans is unknown, although it is known that the Celestials conduct similar experiments on other races such as the Skrulls.

Each race that the Celestials has experimented on is periodically assessed by Arishem the Judge, and if a race "fails" by Celestials standards, he sends Exitar the Exterminator, a 20,000 foot tall Celestial to carry out the sentence. Sentences can go from the terraforming of a planet into a garden paradise, with part of the inhabitants being destroyed, and the survivors being given a second chance to the destruction of a planet along with its population. The Celestials policy of interference is the exact opposite of the Watchers policy of observation, and the two races have been enemies for many eons.

Source: Marvel Universe “The Eternals”