The Imperium of Midgard is the largest organized imperial body in the Universe, led by House Major-Saturninus. This massive Empire holds power over 99+ quadrillion worlds and are by far the greatest superpower to date. The Imperium is religious in nature, worshiping a pantheon of Sovereign Gods, celestials who take no side in either Radiance or Darkness. The Imperium opposes the breaking of the 7 Sacred Seals and believes that doing so will usher in a new dark age for all people.
The United Stellar Commonwealth is the largest governing body with the power and numbers to oppose the Imperium. They control 81+ trillion worlds but reject any form of unified governing power, allowing most sectors to rule themselves with a loose set of general laws. The Commonwealth is not officially religious and regards deity worship as taboo and dangerous as faith can blind and bind one's mind. They view the 7 Sacred Seals as the lies of old religious zealots who want to keep Midgard below all other Realms.
The Knights of the Iron Order are an old sect of Knights hailing from the previous Multiverse who witnessed the Burning, only escaping such a fate via their own engineering. The Order controls roughly 1.2+ million worlds, each guarded by an Order of Knights responsible for it. They know of Yibbithal and yet work to ensure the 7 Seals are never broken and Chaos does not come to rule Midgard. They are semi-religious in nature but do not worship celestials.
The Hisui Raion Syndicate (Jade Lion) is a massive crime, marauder, and pirate syndicate which formed to control the vast stretches of space the bigger powers could not police. They officially are estimated to only directly control 13+ trillion worlds, but they have massive influence everywhere. HRS has no personal stake in religion or Yibbithal, too busy controlling the criminal underworld.
The Temple of Khaos is a religious movement that seems to worship the primordial Chaos forces of existence, held only at bay by The Author and his Story Machine + Chains of Fate. They know of Yibbithal but have their eyes set on the Dhastra'Kabid, a messiah-like figure in their doctrine who will defeat the Author, break his Story Machine, and tear down The Veil so that Chaos may once again reign.