The-One-Above-All is the Living Tribunal's boss, and it was never stated that it was the writer/editor, it was just stated that the writer was God.
The One Above All however is the Celestial leader.
* The One Above All — The leader of the Celestials. Not much is known about him; however, both X-Factor and Thor have encountered him. In particular, he has rescued Gilgamesh the "Forgotten", after a Deviant nuclear bomb (Eternals #13), and dispatched him to Olympia to tell both Eternals and gods not to interfere in the Celestial's judgement. In the subsequent battle will be involved Thor and Uni-Mind. (The Mighty Thor v1 #287-291).
Not to be confused with the entity of the same name whom the Living Tribunal answers to. - First appeared in The Eternals (1976 series) #7
The One-Above-All is a fictional character appearing in the comic books published by Marvel Comics. It is considered to be the supreme cosmic entity in the Marvel Universe cosmology. The One-Above-All should not be confused with the alien Celestial with the same name.
Above all pantheons of gods, cosmic entities and even beyond the Living Tribunal and Franklin Richards, and even the Phoenix Force is the ultimate supreme being, the One-Above-All, to which the Living Tribunal sometimes refers. He is considered "God" to the Marvel Universe, and is rarely seen, but referred to in times of dire need.
The One Above All is fully omnipotent, omniscient, omnipresent and has totally unlimited reality-shaping powers. The One Above All has shown the ability to create new universes on a whim. His power surpasses everything in this multiverse.
Guy is a fan of Celestials. If u believe Celestials are Eternity's creation. I smile. If u believe in the theory of the Absolutes, like I do. Reading X-51 #11-12, they are not the same age as the Watchers. They are indeed older. TOAA is the leader of the Celestials