Herbert Dunwich is the author of the book The Strange Tribes. The contents of the book are the notes Dunwich made during a study of the customs of the Horrors inhabiting the Cursed Archipelago. Dunwich observed the Horrors from afar, as he considered them too aggressive to approach directly. When he had the opportunity, he also studied their artwork when none of them were around. This way, he was able to learn of the horror deities Uvhastur, Yogsathla, Nyarlahydra, and their chief deity Tezcasathla.
Dunwich generally held a negative view of the Horror gods and customs. Tezcasathla filled him with a particularly strong sense of dread. Dunwich came to believe that Tezcasathla had another, truer, name, which had somehow infected his soul. Although he refused to write the name, believing that doing so would infect his readers, he finished his book with "do I really think I can save you", a phrase associated with Xau-Tak.