Zanassu the Spider Demon is a demon lord, in the Dungeons & Dragons roleplaying game.
Zanassu was first described in Empires of the Sands (1988).
His death was mentioned in the Empires of the Shining Sea boxed set (1998), and in Demihuman Deities (1998).
Zanassu the Spider Demon was said to rule over the evil creatures of Spider Swamp. He was later reported as having been slain by the drow god Selvetarm.