Lord Marrowgar is the first boss of the Icecrown Citadel raid. Pieced together by the Lich King from the bones of a thousand vanquished adventurers, he is the guardian of the Frozen Throne within The Spire, and wields the power of the throne itself.
The lich Lady Deathwhisper is the Supreme Overseer of the Cult of the Damned and the second boss of the Icecrown Citadel raid. The fight is mostly a DPS race (with a high damage output it becomes significanty easier), but also requires high awareness from all raid members.
After falling to Frostmourne at the Battle of Angrathar the Wrathgate, Dranosh Saurfang was raised in undeath by the Lich King and brought to Icecrown Citadel. Imbued with the power of the Scourge, the Deathbringer bars the way of any attackers trying to enter the Upper Spire.