The Fiery One was a figure in the theology of the people of planet Obsidian, who was the personification of evil. The Fiery One was normally depicted as a male with red hair and flames for eyes. In 2296, the Vulcan Sered convinced the cult of the Faithful he had formed around himself that Spock was an agent of the Fiery One, working with Starfleet against them. (TOS novel: Vulcan's Forge)