Megaverse

The megaverse was the sum total of all universes and multiverses connected to the Star Wars Universe.

History
13.8 billion years prior to the Battle of Endor, the Big Bang occurred. From the Big Bang, the familiar universe came into existence. This universe, however, was only one of many universes -- a multiverse -- and this multiverse, in turn, was only one of many multiverses. Together, this collection of related multiverses is known as the megaverse.

The cosmoses of the megaverse all share the same physical laws, though the physical constants vary between them. Each are connected to the Force, which allows life of some manner to flourish within each of them. Time is immutable in them all; what has been and what will be is fixed and cannot be changed.

Though exceedingly difficult and dangerous, travel between the multverses and their respective universes is possible.

Multiverse-0
This is the multiverse of the Star Wars Universe and all variants of the Star Wars Universe.

Types of Multiverse-0 universes
Hubble volumes

1,000,000+ spherical regions of spacetime, each with a radius of 1.1 X 1031 cubic light-years, which make up the entirety of observable and unobservable space. With the expansion rate of the cosmos being greater than the speed of light, the volumes are largely incapable of observing one another through conventional means, essentially rendering them separate universes. Convergent stellar evolution has conspired to create varying similarities between the various Hubble volumes, making many of them near-duplicates of one another.

Pocket universes

Regions of spacetime within any of the Hubble volumes -- usually no smaller than a solar system and no larger than a galaxy -- which have been pinched off from the greater cosmos, effectively separating and isolating them from it.

Though some of these pocket universes occur naturally, most are the creations of intelligent agencies.

Parallel timelines

When the Big Bang occurred, an infinite amount of parallel timelines were created. While only one of these timelines managed to coalesce into a tangible, living cosmos, the remaining infinite continued on, existing as visions of universes which could have been.

While Force-sensitives and psionics from the multiverse proper can sense or look into these timelines, the worlds themselves cannot be physically entered or their inhabitants interacted with as they are little more than ephemeral shades without real substance.

List of Multiverse-0 universes
Below is the list of known catalogued universes.