The Entity
The Entity was a mysterious five-dimensional entity.
Its true form was inconceivable for human minds; in 5D Space it was visible as a huge Pac-Man-like creature devouring duplicates of the Earth (each representing a whole parallel universe). Within one Jenny Everywhere's theory that the whole Multiverse was actually a quantum computer simulation, she speculated that the Entity was a visualisation of the process of the compute clearing its cache after completing the calculation of a given universe.
After learning of the threat the Entity presented to Creation, this Jenny built the Lotus Prime and recruited four other incarnations of herself. Pooling their shifter energy, the five Jennies were able to travel into 5D Space, and, there, bother the Entity enough to drive it to change its course away from populated universes and towards strings of “dead,” uninhabited ones. However, they were unable to do any significant damage to the Entity. (COMIC: Makeshift Multiverse)
Behind the scenes
It is possible (though this was likely not the intent of the various creators involved) that the Entity is the same being as the Destroyer from PROSE: Where Is Everywhere, and/or as the Living Black Hole from COMIC: The Secret Origin of Jenny Everywhere.
