Boy/Girl something like that exists on the wiki called Godvesre and besides why it must be a sans it can be always a celestial being or something/someone else.
Ps: don't take this comment too personally or seriously.
Welll toby fox is the creator of undertale, the creator of all (multiverse, dimension etc) is sans/the creator
Anso sans/the creator is not a sans
Having an omnipotent skeleton that created the entire omniverse? Seriously?
I'm open to many things, but I'm not having a Sans be the creator to the omniverse.
Also, Alterna Team, Sans/The Creator is a Sans since they literally look exactly like him.
He is not a sans, he is very very different from what he looks like
Here is what makes a character a Sans:
Sans-Like Body (This Can Include only Skull)
Eyelights
The Literal Name Sans in It
Sans Teeth
And if you want to go down on the cringe Fanon Sans route, you can also have ecto-limbs or flaming eyes.
What do you think?