The Dark One is the leader of the Iceborn Orcs. He is known for his strength, size and fierceness as a leader and in battle. Little is known of where this orc came from, but since his emergence as the Iceborn leader, they have steadily fought across the Barrens into the Sea of Sand and, most recently, into Easterly.
Most recently, the true nature of this orc has been put to question. A seer named Janka Shohlam of the Vanguard believes that his orc is not as he appears. His seeming invulnerability in battle gives weight to this concern. The Vanguard are focused on understanding who he is so they are better prepared for the fight against him and the Iceborn.