Duat is the Egyptian realm of the dead that often features in the cosmology of supernaturals originating there.
Mummy: the ResurrectionEdit
Mummies and their allies use "Duat" as another name for the Underworld, where every mummy's ba soul spends a certain amount of time between resurrections. Specifically, it refers to the Dark Kingdom of Sand, which was once ruled by Osiris; after the Sixth Great Maelstrom, most of this Dark Kingdom is engulfed in a brutal sandstorm, but A'aru remains protected by Anubis and the Judges of Ma'at. 
Vampire: the MasqueradeEdit
The Followers of Set also use the term Duat to describe an otherworldly realm, though it differs what exactly it entails. The Elder Shenebti describes it as a river that springs from the waters of the Primeval Ocean Nun (sometimes identified with the Tempest, at other times with Outer Space), that is the home of the dead that have not yet been weighed. Into these waters, Set was cast after Horus had bested him, and here, he killed Apophis and ate his heart. During the Dark Medieval, some instead believed Duat to be the literal afterlife, which was imagined as a mirror of the living world. Through the designs of Ra and Osiris, the Ma'at between both realms is disrupted. The Clan claimed to combat this by striking against civilization, the chief tool of Set's enemies.
Blood Sorcerers of the Clan speak of Duat as a realm more in tune with Shenebti's tale. Duat is a realm of 12 great caverns filled with lightless fire and dark waters in which serpents, demons and other monsters live. Its only light being the passage of Ra's ship. The dead that have not yet reached the Western Lands are consigned to a state without breath or motion until they are delivered. This realm is under the dominion of Seker, while Osiris rules the Western Lands where the soul goes after having been weighed against the feather of Ma'at. Among the monsters that live in Duat, Apophis is the most renowned, but others exist, like the sebau, who manifest as snakes, crocodiles, or hybrids of both with human parts.
Werewolf: The ApocalypseEdit
Werewolves call the Umbra surrounding Egypt, demarked by structures called the Four Towers, Duat (sometimes also Tuat) and the Silent Striders sometimes use the term to refer to the Umbra in general. Since the Umbra in Egypt has a strong connection to the Dark Umbra, its influence permeates the region, making entry into the Shadowlands more easy.