The Fates

The Fates are the ones who created the Everything is Connected Multiverse. They have infinite power over everything in every universe, and control every character. But they usually don't interfere directly with any game.

In real life, they are Daniel and Jake Bell.

History
The Fates created Albert at the start of the Multiverse. Albert tried to rise up against the Fates, but they created Trebla to fight him in an infinite battle.

Gaster's Rise
The Fate Daniel gave Gaster the power to return to the Undertale Universe and destroy it. However, after Gaster found his way to an alternate Pokemon Universe, Daniel let him be defeated by a Pokemon battle, and reset the timeline of the Undertale Universe, bringing it back.

Knowledge of the Fates
Not many people know about the Fates. However, they do reveal themselves to a chosen few.

The Tribe of Fate
Daniel revealed himself to a tribe hundreds of years ago, and instructed them to build a temple with the history of the Fates written inside it. This temple is the Ruins of Al in the Zepplin region.

Albert and Trebla
As Albert and Trebla both know that the world they live in is just a game, naturally they know of the Fates.

Bill Cipher
Bill Cipher learned about the Fates from overhearing Albert and Trebla talk about them for millenia in the Void. However, he doesn't care that he's being controlled.

Gaster
Gaster talked with Daniel about destroying the universes. After he was betrayed, he swore revenge on the Fates, but was ultimately killed by Yubam Endall.

Trivia

 * The title "The Fates" comes from Greek mythology, or more accurately, Percy Jackson. Daniel gave this name to them to throw off Jake and Luke when playing Pokemon Broken Time and Shattered Space.
 * Jake's Fate comes from the Studio C sketch "Lobster Bisque".
 * Daniel's Fate is based off of Professor Daniel from Pokemon Selenic.