Energy beings that once had physical bodies, but have grown beyond them.
The beings which created the monoliths have long-since abandoned physical forms and instead live as beings of energy on the surface of their star.
The President of the Time Lords, Rassilon, a resurrected mythological figure, attempts to turn the Time Lords into beings of energy so they can govern the universe and destroy any enemies.
The entities encountered by the crew of Endurance are future humans who have become energy beings, returning to their own past to shape their future.