The universe was said to be the biggest thing but that's not entirely true for you see for you see a theory known as the multiverse is added to
the chart

Now for those who are christian believe of an afterlife place known as heaven but were not going to explain any of these
Post in the comments below of which do you think is bigger than the universe and who knows maybe there are bigger things out there waiting for us in the dark even are own pony OCs.
Well, I've heard of the multiverse theory, but I have another, even bigger one. If the multiverse is a conglomeration of other universes, in the way a solar system is the conglomeration of a bunch of planets, then could there be an OMNIVERSE, a conglomeration of other multiverses?
...of course, this is assuming that size and spatial rules actually apply to alternate universes and such. Maybe they're all the same size and occupy the same space at the same time in different phases or whatever. Or maybe they aren't. I'm no Q or Discord, so I can't really say for sure. Although imagine this: suppose our entire universe is like an atom in the great scheme of things, and there is an entire universe of other atoms like it. Think how cool it would be to go exploring all that! It would virtually never end!
Now... how to get my hooves on a TARDIS.... :D