Nerull
Nerull is the God of death, darkness, murder, and the underworld. He is known as the Reaper, the Foe of All Good, the Hater of Life, and the Bringer of Darkness. His symbol is a skull and scythe. Nerull is usually seen as a black-robed skeleton, with a rust-red body and green, ropy hair. He carries a staff called "Lifecutter" that at his command grows a scythe blade made of scarlet energy. His alignment is Neutral Evil. Nerull is the patron deity of those who seek the greatest evil for their own enjoyment or gain.
As the Skeleton King
In 340 A.B, Nerull left Arborea to return to the Mortal Plane where he forged The Necropolis, a physical place in which souls traverse to enter their respective spirit planes. Here he reigned as its ruler and protector, allowing mortals to retrieve the souls of their lost companions for a price, usually something outrageous that Nerull desires for his own amusement.
In 421 A.B, The Five Uniques came to Nerull to ask for the soul of Emelia. The Skeleton King offered her soul in return for purging a corrupt soul from his lair, which they managed to do after enraging the King and feeling just a small amount of his power.
In 422 A.B, The Five Uniques requested Nerull's help once more, though he made a sinister request that would later effect Feng Longskull most of all: The soul of Feng's sister. This put Feng on a war-path with the ancient God for the rest of his mortal life and beyond.