Death: Guardian of the Gate

From publisher blurb:

A sourcebook dealing with the death domain. Includes info on a goddess of death, worshippers, churches, myths and legends, along with crunchy prestige classes, spells, and other things designed to help you flesh out the shadowy figure of death in your home campaign. You can either use the Lady Pale as she is, or you can borrow ideas to flesh out your own campaign's deities.