Celestials

"These Stones, it seems, can only be brandished by beings of extraordinary strength. Observe. These carriers can use the Stones to mow down entire civilizations like wheat in a field."

- Taneleer Tivan

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.

History
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 Power Stone as a means of execution against those who wronged them. Knowhere, a spaceborne mining colony, is actually the severed head of a deceased Celestial.

Characteristic Traits
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.

Trivia

 * 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.