The Builders are a hyper advance race of humanoids who are considered to be oldest sapient species in the
Humanoid in appearance, a typical builder's body is incased in a very hard bony carapace which they use for protection. The builders species is split between two difference forms called the Creators and Engineers. The Creators resemble insectoids with a large bony head and large set of eyes while the Engineers are more human-like.
The builders are said to been exploring space long before the watchers and by the time mutants start appearing on earth they had already explored over 5000 realities. As they explored space, the Builders created whole worlds and races seeing that the universe needed to be cultivated by them. For billions of years they seeded life across the universe on worlds such as Earth and directed the evolutionary history of the Kree, Skrulls, humans, and many others. They also created other races as caretakers in their absence such as the Curators, Caretakers, Alephs, Gardeners, and Abyss.
At one point in time the the Builders were at war with the Beyonders as they sought to destroy the multiverse.