Glaaki was created by Ramsey Campbell in "The Inhabitant of the Lake" (1964). It appears as a vast ovoid mass studded with metallic spines, lying dormant at the bottom of a lake near Brichester in the English Midlands.
Glaaki impales victims with its spines to convert them into immortal but steadily decaying undead servants. These servants compile and preserve the "Revelations of Glaaki," a series of volumes containing forbidden knowledge.