Emerald Empress is a member of the Fatal Five and an enemy of the Legion of Super Heroes. She can control the mystical Emerald Eye of Ekron which is the source of her powers. The Eye can emit energy blasts, allow her to survive in space and also fly.
For the Legion of Super Heroes cartoon Emerald Empress was voiced by Jennifer Hale in all appearances for season 1. For the season 2 episode 1 she was voiced by Tara Strong.