Spawn of Azathoth, subtitled Herald of the End of Time, is a supplement published by Chaosium in 1986 for the horror role-playing game Call of Cthulhu.

As the adventures unfold, the Investigators will learn of a plot to destroy a guardian who has protected the Earth from incursions by "seeds" from the Elder God Azathoth.

[1] The first edition of Spawn of Azathoth, written for the third edition of Call of Cthulhu by Keith Herber, with contributions by Sandy Petersen and Lynn Willis, a cover by Susan Seddon Boulet and illustrations by Kevin Ramos, was published in 1986 as a boxed set consisting of three books: The second edition, published in 2005 for the 6th edition rules of Call of Cthulhu, is a 200-page softcover book with the original text and handouts supplemented by contributions from David Conyers, Don Coatar, Jeff Carey, and Steve Hatherley, additional illustrations by Mislet Michel, Andy Hopp, and Paul Carrick, and new cover art by Tom Sullivan.

In the November 1986 edition of White Dwarf (Issue #83), Peter Green thought the campaign "gets off to a nicely horrific start" and followed up with "enough horror here to send even the most hardened Investigator insane, and lots of good detective work is called for to piece the story together."

However Green thought that compared to the well-received adventure Masks of Nyarlathotep, this boxed set contained much less material, and that "some useful pieces of information seem to have been overlooked."