Saga was a female synthetic lifeform created by Doctor Altan Soong on Coppelius. She had a "twin sister" named Arcana. (PIC: "Et in Arcadia Ego, Part 1")
Sutra killed Saga by stabbing her through the eye while she was restrained by Narek. Dr. Agnes Jurati later stole one of Saga's eyes to bypass a retinal scanner and break Jean-Luc Picard out. Soong was able to reconstruct Saga's memories and learned the truth from them about her death for which he deactivated Sutra. (PIC: "Et in Arcadia Ego, Part 2")
Saga was played by Nikita Ramsey.