Published by Marvel Comics, group of incredibly powerful aliens who travel the universe experimenting with various races and generally messing with the destinies of entire worlds, which is something you can do if you are two thousand feet tall.

The Celestials have had a huge impact on the Earth, having visited it on four known occasions. The first was millions of years ago, during which the Celestials evaluated the human race's potential. Finding it worthy of continuing, the Celestials left, but not before monkeying with humanity to allow it to beneficially mutate and to create two off-shoot races. One became known as the Eternals, who were extremely long lived, possessed enormous power, and were practically unkillable. The other really never had a chance but to be second rate, having been hung with the label Deviants. The Deviants were an unsightly group with wildly varying genetic code. It was quite possible for two Deviant parents to have a child that shared none of their traits (i.e. warthog man + really ugly woman with a fin running down her head = little girl that looks like a cross between a squid and a chihuahua). The Celestials left the Earth and returned many years later.

Upon the return (which is known as the Second Host of the Celestials), the Celestials evaluated the Earth and the three groups they had left. The Eternals and humans got passing grades, but the Deviants were given a cosmic "does not play well with others." Where in kindergarten this gets you a time out and no cookies with your juice, with the Celestials, it gets your continent sunk. In this case, the continent of Lemuria, but they also threw in sinking Atlantis for free. The Celestials then departed again to return a mere 1000 years ago.

Upon their third visit, the Celestials were greeted by the Eternals and the Asgardian gods who informed them that they were tired of the Celestials showing up every couple of thousand years, making judgments as to how fit their races were to survive, drinking all their beer, making some long distance calls and then taking off. The two groups from Earth challenged them to a showdown, but you don't get to be a group called the Celestials by putting up with a bunch of gods lead by a guy with one eye who considers a couple of ravens pets and a bunch of Greek god wannabees. The Celestials cleaned the Asgardians clocks and departed again to finally return for a final time in the modern age.

The Celestials judged the human race after the start of benevolent mutations, picking people from different eras who they took with them to teach, giving them special powers and calling them the Young Gods. The Celestials have since departed to return the next time the Marvel writers need a really big plot device.

The Celestials appear as two thousand foot armored figures, each of which has a particular function. Their names are such things as Arishem the Judge, Exitar the Executioner, and (one of my personal favorites) Oneg the Prober. One has to wonder if wherever the Celestials come from if there are Celestials named Poktar the Security Guard, Nazbeq the Accountant, and Faalooq the Air Conditioner Repairer who don't get to travel around the galaxy.