Abyss Princess.

+Doesn't have a beginning, middle OR end, she exists outside of time and space and as such is impossible to kill.
+Exists in all realms of reality and all periods of time at the same time, making her omnipresent and omniscient.
+Will feed on the souls of your enemies, and their families, AND everyone who happens to be nearby them.
-Looking at her will probably cause you to go insane.
-If you anger her she will destroy the entire universe.