The Powers That Be multiverse is a collective multiverse created by Evilhumour (who also has a page on TV Tropes) and co-written by AnoneMouseJr and Tangent.

It is currently divided into sixteen primary universes, with the possibility of more; all are linked in ways that are not obvious at first. The primary linking factor, however, is the presence of the Powers - a set of entities with a Purpose, Role and Duties in their respective worlds, which are unknown to the greater population but include such beings as Day, Night, Death, Harmony and Harmony's six sub-Powers: Honesty, Kindness, Laughter, Generosity, Loyalty and Magic. These universes and their extant stories (not counting some planned sequels) are as follows:

* Blinds-verse (rated M; NSFW) - #1 (Close Your Blinds!); 2 (A day in Ponyville).
** In a universe where characters are the opposite gender from canon, romance is in the air, and Rainbow Blitz (counterpart of Rainbow Dash) and Elusive (counterpart of Rarity) need to be more careful about their surroundings before they hook up.

* Broken Star-verse - #1 (Look to the Past).
** The pony tribes and their alicorns are rather different in this universe. In the first story, we follow the bat pony Snarling Fang, the flutter pony Tough Love and their journey together as they discover what fate has in store for they and their future foals.

* Cassius-verse - #1 (Cassius's Story).
** Bat pony teenager Cassius, nineteen-year-old son of Lunar Guard captain Cold Justice, moves to Canterlot with his father to live after Luna returns, but finds himself having to deal with some very complex issues involving batpony reputations and his own personal life.

* Diplomacy-verse - #1 (A Diplomatic Visit); #2 (Diplomat at Large); #3 (Diplomacy Through Schooling), #4 (The Diplomat's Life).
** Ponyville gets an unexpected visitor: Swift-Pad, a diplomat from the wolf packs, whose teachings inspire Twilight to become a diplomat herself, helping reforge the bonds of friendship between all nations. Later, after returning home, she announces her intention to open a school, inviting students from around the world to come and learn the ways of friendship and the cultures of other nations.
*** Series officially completed as of 8/27/20.

* Doa-verse - #0 (A Winter's Tale; prequel); 1 (Escape from the Moon); 2 (The Mare From the Moon); 3 (The World Left Behind), 4 (Scavenge for the Future).
** An alicorn mare awakens to find herself on the moon, with no memory of her true identity and a burning desire to uncover the truth... in the sequel, Doa’s discovered her true identity, but runs into unexpected complications.
** The prequel tells the story that Snöflinga told off-screen in chapter nineteen of The Mare From the Moon.
** Story #3 picks up on the Equestrian side of things, following chapter 27 of The Mare From the Moon.
** Story #4 is the finale, picking up thousands of years after the end of The Mare From the Moon.

* Galloping Waves-verse - #1 (The perfect day); 2 (The Adventure of Galloping Waves).
** Princess Celestia and Princess Luna have a bit of a rocky history with their parents, who decide to make amends by giving their daughters, and Equestria, one perfect day. In the second story (under heavy revision), Luna’s son Galloping Waves finds himself involved in some unexpected adventures.

* Harvest-verse - #1 (Death is forced to take a vacation).
** Fall Harvest, the Death of Alicorns, is forced to take a break from his duties and visit Equestria, where he shares his history with Princess Twilight Sparkle and her friends.

* Pieces-verse - #1 (The Pieces Lie Where They Fell); 2 (Picking Up the Pieces).
** A thousand years after A Canterlot Wedding goes horribly wrong, resulting in the deaths of nearly everyone there, a new set of Bearers are chosen. The sequel picks up right where the first left off, dealing with the aftermath of the new Bearers' debut, the consequences of their actions, and complications old and new in their respective personal lives... and the dangerous threats that lie ahead.

* Reflecting Shield-verse - #1 (Reflecting Shield).
** Years in the future, a unicorn named Reflecting Shield crosses paths with Princess Cadance and finds herself caught up in some unexpected events.

* Survival-verse - #1 (Survival).
** Over two months ago, an old monster was found and caused unspeakable damage to the nation of Equestria, which is now threatened by an undead hoard. With Celestia missing, only Princesses Twilight and Luna are left to try and keep Canterlot alive while they search for a means to end the threat…

* Suspenders-verse (rated M; NSFW) - #1 (Suspenders); 2 (Shorts); 3 (Three Ways); 4 (Apple Coloured Rainbow).
** In a world where the ponies are anthropomorphic and some genders have been swapped, Applejack (female) and Rainbow Blitz (male) find themselves becoming a couple.

* Testing-verse (primary) - #1 (A simple test from the bureaucracy of Equestria); 2 (Back to school for Lulu!).
** Luna's return brings with it complications, and an academic proficiency test for the right to maintain her position in the government. In the sequel, she must attend Ponyville Elementary... with Shining Armor also in attendance as her personal bodyguard.

* Testing-verse (divergent) - #1 (A simple test from the bureaucracy of Equestria); 2 (Teaching the Moon).
** An authorized alternate ending and continuation by Tangent, diverging near the end of the original story. When she hears about Luna’s test results, Twilight Sparkle figures out an alternative solution: as the equivalent of a home-schooled student, Luna doesn’t need twelve years of public schooling - she needs one year under a private tutor. Princess Celestia, loving the idea, promptly assigns the role to Twilight… and sending Luna to Ponyville as Twilight’s new apprentice.

* Twisted Fate-verse - #1 (Twisted Fate).
** When Celestia and the Bearers are captured by a dream demon and imprisoned within their worst nightmares, Luna must enter their dream worlds to save them.

* Two Moons-verse - #1 (A Chance Meeting of Two Moons).
** Princess Luna goes to her private realm to vent after an argument with Celestia. Meanwhile, in his own dimension, Prince Artemis gets into a similar situation with his brother Solaris. Cue complicated relationships as the two counterparts meet and start to fall for one another… while a dangerous threat lurks in the background.

* Worlds-verse - #1 (A Moon and World Apart), 2 (A Moon and World Together).
** Luna and Celestia's fight took a rather different turn from in most universes. Instead of assuming a corrupted form, Luna took those who supported her and left for the moon, where she and her followers still live a thousand years later. But sooner or later, worlds must collide, and when the ponies of the moon meet the ponies of Equestria, the sisters' conflict won't be so easy to resolve.