Jacques Collin de Plancy was a French occultist, demonologist and writer. He published a number of books on occultism and demonology. The most famous of these books is probably his “Dictionnaire Infernal”. The “Infernal Dictionary”, as it is known in English, is a book on demonology describing demons organized in hierarchies. The book first appeared in 1818 and it went on to have several editions.