Dagon
From The Griffin's Crier
A creature who existed before demons, before gods ... and which has a strong connection to the Far Realm. It is believed that the Undreamers are attempting to use the will of Dagon to subvert Obsidian Bay, transforming it into a beachhead of the Far Realm on the Prime Material Plane.
Mindflayers are either associated with, or worshipers of Dagon. The Demon Ylerys is said to have been his herald.
