Necropolis

Centuries ago, when Earth's Darkfolk – vampires, werewolves, witches and other creatures –  were threatened by humanity, they departed our planet's dimension and journeyed to a shadowy realm, where they built the great city of Necropolis.

Matthew Adrion is an Earth cop who came through a portal to Necropolis on a case, died, and was resurrected as a zombie. Unable to return home, he works as a private investigator on the very mean streets of this shadowy, dark city.