Lady Sinestra

From Twilight Wiki

Sintharia, also known as Sinestra or Lady Sinestra, was the former prime consort of Deathwing and mother of Nefarian and Onyxia. She was, until recently, believed dead. Her experiments led to the creation of a flight of twilight dragons which she planned to use to rule Azeroth. Her plans never came to fruition, and her death finally came at the hands of her own creation, the twilight dragon Dargonax.