I'm going with the Kah-Gash.
Okay.
Sit down son.
Get prepared to listen to a bunch of dumb bullshit.
The original universe was shaped like a chess board. If I recall correctly, demons inhabit the white spaces and these weird magic god things called "Old Creatures" kicked it in the black spaces. There was a barrier keeping the two separate, the Kah-Gash. For eons the demons and the old creatures weren't aware of one another's existence, and it was radical. Then the demons were like "no" and they started crossing into the black squares. The old creatures got owned. This put strain on the Kah-Gash, and it eventually broke and sparked the motherfucking Big Bang. Now, there were two separate universes, one for demons, another for old creatures and inhabited planets such as earth. The Kah-Gash's pieces moved from life form to life form, across both universes, since the dawn of time.
The demons wanted to collect the pieces in order to regain their immortality. Human Magicians sought after the pieces so they could wipe out the demon universe.
That brings us to Grubbs (Magic Werewolf man), Kernel (Black guy with fancy interdimensional portals), and Bec (chick who's thousands of years old and knows everything, ever). Some fucking how, by the most bullshit of odds, the three pieces meet up. When they come together, they shoot loads of universe bending goo all over the god damned place. It's literally the most OP shit ever.
Wait.
No.
Hold on.
It gets even more OP.
Each piece of the Kah-Gash represents a factor of how the Kah-Gash operates. Grubbs is the trigger, meaning he executes the actions. Kernel's the eye, meaning he's able to see... things, and Bec's the memory, meaning she knows and remembers everything, ever. As a last ditch effort, they tear the universe apart, then trigger another big bang. Because the memory remembers every factor of the former incarnation of the universe, the sentient Kah-Gash can shape the universe to be whatever the fuck it wants. It can make it so none of your characters exist in the first place.