Oh, the genealogy of Campbell's Hero with a Thousand Faces is one part Mircea Eliade, writer in comparative religion, and three parts Carl Jung, famous psychoanalyst/depth psychologist. Both of them, although quite respectable authorities in their own right, have been criticized by scholars in recent years for their reliance on superficial patterns of similarities among myths from different culture that are really only similar in the scholar's reconstruction and not in their original forms. This discovery of patterns is generally traced to nineteenth-century anthropologists like E.B. Tylor, but was most widely popularized in James Frazer's The Golden Bough .

A good look at the critique if you're interested is George Stocking's Victorian Anthropology .