The Celestials were an ancient race of armored, god-like beings who were present long before the dawn of the galactic communities and even the Dark Elves and Asgardians. They were notorious for using the Infinity Stones.
The origin and nature of the Celestials is shrouded in mystery. Whatever was known about them is known only to a few, such as Taneleer Tivan. The Celestials used the Infinity Stone known as the Orb as a means of execution against those who wronged them. Knowhere, a spaceborne mining colony, is actually the severed head of a deceased Celestial.
The Celestials are gigantic humanoid beings. While the most that have ever been seen of a Celestial are severed extremities and a video clip from the Collector, the clip shows them as armored, humanoid giants.
- In the comics, the Celestials were deeply involved in humanity's early development, and were responsible for the creation of the mutant X-gene, the Deviants and the Eternals, the race that includes Thanos.
- In the comics, the Celestials were the cause of, and one of the few surviving races of, a disaster that essentially completely reset the universe. If this remained true in the movie universe, they would be, by definition, some of the oldest living things in the universe.