Overmonitor is a gigantic vast intelligence named Monitor but referred to in places as "Overmonitor" or "Overvoid", discovered the Bleed and the DC Multiverse within, a 'flaw' at its heart.
In the beginning, there was only Overmonitor. Until he discovered a multiverse (to him, multiverse is a germ size) that been created by another multiversal race. He sent a probe to explore the multiverse that he has been discovered. To make sure that the multiverse is not destroyed by someone, he make a shelter, The Bleed, and a giant Thought Robot.
Overmonitor is the largest known character in fiction even beat Yog-Sothoth in size because Yog-Sothoth is the size of multiverse while multiverse only size of bacteria to Overmonitor. To him the infinity universe is like a germ world. He is simply a limitless omniversal being.