Not sure if I did this right but

Vee Anchoes

Ages ago, before primordial beings forged the Great Wheel, the Inner Planes were formed. One of the primordial beings that performed this feat rebelled against the others, raging against their plan and was destroyed by its compatriots, fractured and fragmented by its former fellows. This entity was sealed within the Negative Energy Plane, scattered upon the eddies and currents of necrotic energy which flowed through the plane (Knowledge the Planes DC 37). For ages the creature's seal was complete. Then someone called upon the dark energies of the plane to re-animate the dead. And Vee Anchoes was born.

A fragment of the primordial being, twisted beyond recognition, drawn forth into the world, and instilled into a new body, Vee Anchoes hid its mind until its animate form was destroyed. Then this spirit of death hid within the prime material plane, deep inside the bowels of the world and waited. Whenever a creature was animated by necromantic magic a new portion of the primordial was released into the world, and Vee Anchoes whispered to it drawing it into itself upon the destruction of its corporeal form. Thus Vee Anchoes has grown with each undead formed, waiting to obtain sufficient power with which to move forth. (Knowledge the Planes DC 40)

It is said that the primordial entity is responsible for the first wights, creating them to spread undeath and release more and more of it into the prime. It is even hinted that other spawning undead, such as vampires, wraiths, shadows, and ghouls may have their origins within it. Or else that it influenced the gods themselves to create them. (Knowledge the planes DC 43)

Goals:

Once it has grown to sufficient size and power, Vee Anchoes plans to go forth from its hidden pit (Knowledge the Planes DC 37). It will take upon itself a physical form and it will seek out the largest population center, and raze it to the ground, converting its populace into the undead. (Knowledge the Planes DC 40). It will continue this task until it has created enough undead to split the boundaries of worlds and allow the negative energy plane to spill out across reality saturating it with death (Knowledge the Planes DC 43).

Sign:

Vee Anchoes uses the same sign as Atropus because it's appropriate (see Elder Evils page 2).

Malefic Property:

Primal Corruption
The presence of Vee Anchoes taints and twists the world, seeping into the central vitality of those who come nearby.
Benefit: The area around Vee Anchoes becomes tainted causing 1 point of Corruption (Heroes of Horror) the first time it is entered within 24 hours, an forcing a Fortitude save (DC 10 + 1/2 Vee Anchoes's HD + Vee's Cha modifier) every 10 minutes or gain an additional point of Corruption.

Traits/Tactics/Etc:

Vee Anchoes will initially appear in its corporeal form when its sign becomes strong, creating an overwhelming version of its sign within 10 miles. It will attack a major city. If its corporeal form is destroyed Vee Anchoes will revert to its incorporeal form retreating deep within the earth to reform. At this strength even intelligent undead can feel its pull and attempt to control them, allowing a lich or vampire which does not want to see the world destroyed to tell the PCs where (possibly after it's reformed once). Its incorporeal form can be destroyed, acting as a massive strength and constitution draining incorporeal undead. In both forms Vee Anchoes has the ability to command undead absolutely, bypassing all other forms of control.