The Defining Coven was a small, strange coven of type one vampires in World 4: Vampires and Wolves. Unlike most covens, its members did not view each other as family or even as close friends, and they did not live together, meeting only when deemed necessary. Several members left to join the Firelock Coven Guard, and the coven was destroyed when almost all remaining members were rapidly killed by Hunters and their enslaved vampiric captives.
This coven was a strange one, designed for a single purpose. Almost all members of the coven were selected, and invited to join, on behalf of this purpose. They would keep watch on all events in the supernatural world, and if a significant event occurred, they would meet and discuss how to interfere or influence. Among their decisions was the one to support the new world leadership of the Firelock Coven, as shown when they interfered and warned Tomas Reddan of an attack which would have otherwise killed his wife, the Queen Tannith Reddan.