The Creator.

" Oh, you kept the gift i gave you? How sweet of you! ""-The Creator, talking to 400/Invalid in their battle."

Story
In one of UNDERTALE's timelines, the human, who was stuck in an endless genocide loop, RESET so much that the game started glitching out, and some codes began to not work properly. These malfunctioning codes stacked up in a single place once, creating a small and weak creature out of broken code.

After each RESET, more code was broken. Which resulted in the creature growing bigger and stronger, the more code was corrupted.

At one point, there was so much broken code that the small creature managed to gather enough power to get out of there. The creature ended up in the Doodle Sphere, where they watched as their TimeLine began to corrupt, giving him even more strenght. After a while, he noticed pages starting to form around him. He tought he was creating those, which he quickly found out wasnt true. Even then, he decided to call himself The Creator.

Appearance
The Creator is a bunch of goop made out of broken code, which can take any shape it wants. Whoever, no matter what form they use, it is always going to have white eyes and a pitch black body.

Stats
HP: 00000000/-33

ATK: --

DEF: +

Limit Breaker
The Creator is unaffected by any kind of limit set by other beings, even if said being is 9 billion times stronger than it.

ShapeShifting
The Creator can shapeshift into almost anything, altough said thing will allways have a black body and white eyes.

Matter Manipulation
The Creator, just like most of his experiments, can move and change non living objects easily, as long as its not a powerful weapon or anything similar.

Magic Manipulation
The Creator is able to use his nearly infinite amount of magic to create shapes out of it, he can throw them or detonate them, he can make them heal or make them kill, etc.

Value Change
The Creator can change his damage and deffense as much as he wants, as long as he has already reached such strength. For example, he can make his damage lower if he is training one of his creations. Along with this, any healing abilities of his is also affected by this.

Artifacts
The Creator can use his matter and magic manipulation to create a magical artifact, which has special properties, altough most of the time its used to store magic. Those artifacts are commonly gifted by him to those he trusts or for his creations.