Necro is a mysterious and sentient entity in the Guilty Gear series, most notably associated with the character Millia Rage. Necro exists as a living weapon, manifesting as Millia's magical hair, and grants her powerful combat abilities. Although Necro does not speak, it plays a significant role by aiding Millia in battles and shaping her fate. Its enigmatic nature and connection to Millia highlight the darker aspects of the series' lore and the burdens faced by those wielding forbidden powers.