The Grand Alliance of Death
The Grand Alliance of Death in Age of Sigmar, also known as the Forces of Death or just Death, consists of armies of undead and mortal who follow the dark commands of the Great Necromancer Nagash, god of death and supreme lord of the undead.
The goal of the forces of death and their master, Nagash, is to slay all living of the Cosmos Arcane and impose the true order of the dead on all mortal realms, rather than merely confining the dead to their rightful place in Shyish, the realm of the dead.
These armies of death are numberless, driven to undeath from the remains found in tombs and among the corpse mounds of ancient battles.
All manner of undead creatures can be found in the service of Nagash, including the skeletal Deathrattle warriors, the rotting corpses of Deadwalkers, and the ghostly spirits and gheists of the Nighthaunt that haunt the realms.
In the war-torn Mortal Realms there are indeed many unquiet dead. Some have the power to bind the slain to their will, from the most bestial corpse to the most regal of specters.
These revenant armies roam every realm, chilling blades cutting into warm flesh whenever their masters seek dominion over the living.
None can rival Nagash, the Great Necromancer - even Sigmar, the God-King himself, has reason to fear his name.
Flesh-eater Courts - Hidden among the ruins of the Mortal Realms, the Flesh-eater Courts thrive. Bound by the madness of their vile ghoul kings, hordes of mordants spend their miserable lives feasting on the corpses that endless war and the struggles of kingdom after kingdom have wrought.
Nighthaunt - A nighthaunt is an intangible form of undead called a gheist or specter. It is the spiritual remains of a once-living mortal who was afflicted by a magical curse that has twisted him through the pain, bitterness, or regret he has suffered in life to the point where he now only tries to open that darkness transfer to others.
Ossiarch Bonereapers - The Ossiarch Bonereapers are a brand new form of Unlife, built specifically for war and to fulfill Nagash's vision of creating a perfect, endless army to conquer any landmass that will be known as Necrotopia.
Soulblight Gravelords - The Soulblight Gravelords are led by Soulblight Vampires descended from Neferata and Mannfred. While many have diverged into different dynasties and developed many changes, few deny the primacy of Mannfred and Neferata. The two Mortarchs are among Nagash's foremost generals, commanding vast undead armies known as Legions, filled with hordes of corpse warriors and beasts of the grave.