Duke Vallenhal

Duke Vallenhal is a level 73 human Death Knight found in Ruby Dragonshrine in Dragonblight. His unholy energy needs to be drained for.

Trivia
Duke Vallenhal took the place of Orbaz Bloodbane who was at the Ruby Dragonshrine at some early point in the alpha/beta. Presumably, this was changed so Bloodbane could have a bigger role in Icecrown.

His last name might be a reference to Valhalla, the last resting place for dead vikings, or possibly to 80's rock band Van Halen.