Gahet is a Xenos and member of the Cabal. Gahet is from a race known as the "Old Kind", ancient even by the standards of the Eldar. A member of the inner circle of the Cabal, Gahet frequently acts as the organizations mission handler to its agent John Grammaticus.
When Eldrad Ulthran decided to eliminate the Cabal in order to save humanity and find a new path to defeat Chaos, Gahet was one of the first members of the organization he targeted. On an unknown world Eldrad attempted to reach Gahet, enduring a vicious psychic prove in the process as the alien tried to discover the Farseer's plan. However Gahet was stabbed from behind by the real Eldrad, with his previous target revealed to be Barthusa Narek. Gahet's dying body was then reduced to ash by Eldrad's telekinetic lightning.