The Good Guys
Aoife of the Shadows
Aoife is the twin sister of Scathach and her greatest enemy. They were romantic rivals for Cu Chulainn before he met Emer, and Aoife bore him a son. Cu Chulainn later killed that son unknowingly on the field of battle, driving Aoife mad with rage.
She is presumed to live in the Necropolis, leading the Undead assault on Mithryn from a safe vantage point.