Liadrin

Lady Liadrin is the matriarch and supreme leader of the Blood Knights.

The Blood Knight
Lady Liadrin was once a priestess of the light, but renounced her vows after the Scourge invasion of Quel'Thalas, feeling that the light had abandoned the high elves (now Sin'dorei) in their homeland's hour of greatest need. Liadrin's contempt led her to personally volunteer for a radical new project of the magisters: draining the light directly from a captured naaru, named M'uru, whom the blood elven scion Prince Kael'thas Sunstrider had sent back home to Quel'Thalas. Originally nothing more than a being of great power with which to sate their magic addiction, a magister named Astalor Bloodsworn was dissatisfied with this notion. After much studying and experimentation with his fellow magisters, he was finally able to devise a radical new method of transferring the light itself - against its will - to individuals who had not "earned" the right to wield it. Thus, the sin'dorei found themselves capable of wielding the light once more. Liadrin was successful in harnessing its light-imbued power, and thus became the very first of the Blood Knights. Under the leadership of Liadrin herself, the Blood Knights quickly gained popular support within Quel'Thalas; their iron will and ability to manipulate the light being seen as a testament to the sin'dorei's power to some, though greatly disdained by others. As such, a new chapter in Quel'Thalas' history was born.

(This page was adapted from wowpedia.com and is a work in progress)