the one above all is the most powerful celestial NOT GOD!!!! here is a link to a really really good site, clicking on this will bring to a page with bios for ALL the celestials.
Sorry to all thanos fans, but the most powerful being above LT and thanos with his phony heart of the universe is that omnipotent being that appeared for a few seconds in the marvel vs Dc crossover. I think he was the one above all, not thanos (with THU). He's either blue or red, i forgot his color. Thanos is waaaaay over rated. If anyone can get his pic and his name it would be nice. By the way, there is a DC one like him too.
goku-vs-superma
There are two One Above Alls. One is the Celestial whom you're referring to, he's basically the leader Celestial.
The second has only been referrenced, and refers to an omnipotent God. However, showing him would open up a whole new can of worms, it's okay to have Norse, Greek and other deities traipsing about since they're just myths nowadays, but to have the Judeo-Christian God appear would be a faux pas.
DC's come sort of close to this, the Spectre talking about his boss, showing us glimpses of heaven and Morrison's creation Zauriel, but they've avoided showing Him for good reason.
No pics but Im of the understanding that in DC v. Marvel, "The Blue Brother" was originally Marvel's interpretation of the "One Above All." However, this was later retconned.
Interestingly, I believe in Fantastic Four #511, they meet "God" (however may be different than the "One Above All"😉 and it turns out to be the king, Jack Kirby.
Hope this helps.