Gravelord Nito, first of the Dead, is one of the four beings who found the Souls of Lords within the flame, and defeated the everlasting dragons. He acts as a god of death and disease, and is the master of the Gravelord Servant covenant.
After the war with the dragons, Nito presumably returned to the Tomb of the Giants, where he slumbers to this day as keeper of a Lord Soul.
Travelers brave enough to find their way into his tomb can pay their respects and become a Gravelord Servant.
At one point Pinwheel stole the power of Nito. This power was also sought after by Occultists who wished to destroy the other lords using the power of Nito. These events are considered ancient history that fall in a timeline between the fall of Oolacile and the Chosen Undead's arrival.
It is interesting to note Nito's role as the giver and bringer of death seems to put him in direct opposition to those who are undead.