Final Fantasy X
Voice Actor: Julia Fletcher
Lady Yunalesca is the daughter of Yu Yevon and the first summoner to defeat Sin after its birth. To perform this feat, she used Zaon as her Final Aeon, and afterwards (as an unsent) took up her role as the teacher who explains about the role of the Final Aeon.
This tradition continued for 1,000 years until Lord Braska completed his pilgrimage. Although Braska accepted his fate, Auron could not and following Braska's successful vanquishing of Sin, Auron went back to confront Yunalesca. She proceeded to cause him mortal wounds, but that wasn't the end of Auron.
Faced By Her Namesake
Ten years after those events took place, Yuna arrives at Lady Yunalesca's chamber in Zanarkand. However, until Braska, Yuna cannot accept her fate and feels there must be another way. Because of this, Yunalesca decides it's her duty to put her out of her misery, but before she can do this, she is defeated.
After her defeat, and the defeat of Yu Yevon, Yunalesca joins her husband in the Via Infinito.