Name: The Morrigan (Anann, Bellona, and Enyo)
First Appearance: Wonder Woman #605 (2010)
Creators: J. Straczynski, Phil Hester, Don Kramer, Eduardo Pansica, Daniel Hdr
Abilities: God-like power and immortality. Ability to raise the dead as their servants. Power to transform their followers and grand them powers. Mastery of combat. Possesses incredible armies and artifacts.
Backstory: A trio of goddesses of war who claimed the moniker of the Celtic goddess of war as the banner under which they operated. The Morrigan were minions of Nemesis who having grown so greatly in power that she threatened the destruction of the multiverse itself.
Wishing to survive what they saw as the inevitable doom of all things, they threw in their lot with the anthropomorphic personification of vengeance itself who embodies every wish for revenge ever made across all of time and space.
Thus the Irish goddess Anu, the Greek goddess Enyu, and the Roman goddess Bellona would unite in order to carry out the will of nemesis. Raising a massive army, they would seek to slaughter the Amazons. Murder Hippolyta and Philipus. Destroy anyone and everyone that Diana cared about.
All in an effort to make Diana to become driven by vengence, turning her into a puppet. An avatar of the goddess Nemesis. So that she may bring about vengence on all and destroy anything and everything.
With numerous minions from centaur, to minotaurs. Immortal Spartans and thousands of modern day soldiers. The Morrigan had the resources and the power to become a most terrible enemy for Wonder Woman.