Helen Vaughan is the villainess in the novella The Great God Pan written by Arthur Machen. In the story, Helen is the offspring of The Great God Pan and a mortal woman named Mary. As an adult, Helen uses her mesmering beauty in order to seduce and marry several wealthy men. Helen then asserts her influence over these men and makes them her accomplices in various debauched affairs. As a result, all of her husbands end up broken, mentally as well as economically and ultimately commit suicide. The exact motivation behind Helen's actions remain unknown.
- The Great God Pan was a major inspiration for Lovecraft's story The Dunwich Horror.