Created by Jack Kirby in 1976, The Eternals are a long-lived race of beings that were created by the powerful Celestials millions of years ago.
The Eternals haven’t been directly addressed in the MCU yet, but Thanos is an Eternal-Deviant hybrid, hence why in the comics he doesn’t look human like most of the other Eternals.
The Eternals were the result of a genetic experiment that also saw the creation of the destructive Deviants.
Thanks to their accelerated evolution, the Eternals are long-lived, can’t be hurt by extreme temperatures, are immune to disease and poison and are imbued with cosmic energy that can be channeled into a number of special abilities.
…
The Entire Marvel Cinematic Universe Explained In 6 Minutes