No one can beat The One Above all when we talk about his true form, he is the Marvel Comics writer himself, he is literally every Marvel Comics writer/reader/editor reigns over the house of ideas, the highest rung of the Marvel Hierarchy, everything else we see in the comics are simple his avatar/manifestation is a fiction to his true form.
1.SCP-INTEGER (SCP-Foundation)
2 Jehovah (World of Darkness)
3. Giant Corpora of Knowledge (Self-Reference ENGINE)
4. Conceptual Unity (the modal verse)
5. Majestic presence (I/O Visual novels)
6. The Mathiverse ( Flatterland)