The Ancient One

A being (arguably a god, but not neceesarily a conscious creator), that has been around since before time and will likely be around long after the end. 
Time and space distort around it, nothing is immune to it, not beast of burden, nor creatures of sentience, not even creatures of the Veil. If one were to capture a glimpse, it would only be of a tiny spherical focal point floating through the air, with all manner of matter distorting towards it.
Nobody has seen its true form, yet every culture has some sort of reference to it; for the dwarves, it is the oldest mountain in the range; for the elves, the oldest oak in all of Tewledandar. The humans have several tales of an old chrone who nobody can remember, she's just 'always been there', and always been old. 
Of course, the creatures of sentience have only old superstitions and folklore tales to describe this being, never even considering what their true form may be or that it may be anything more than just a tale. For the creatures of the Veil, however, they know better. They too, have never gazed upon the true form of The Ancient One, but they are aware of its existence, and its effect upon on the world. 
Tales of plots and schemes that have gone awry due to impeccably timed actions occuring out of sync, or keenly targeted spells or other arcane assaults going way off their planned trajectory and missing their target are all atributed to the presence of The Ancient One. 
One thing is for certain though; even among the Creatures of the Veil, it is known that one ought never to cross or question the ways of the ancient one, lest they indeed be the creator of all that exists and therefore to contravene their divine plan would be to oppose existence itself, and the implications of that do not bear thinking of.