Exclusive first look: The comprehensive visual history of Dungeons & Dragons Demogorgon. Mind Flayer. These Dungeons & Dragons terms have been thrown out by the characters on Stranger Things to put the otherworldly happenings of Hawkins, Indiana, onto a more understandable plane of existence. Humanity's first instinct when confronted with the unknown is to contextualize it into something the mind can understand. Sure, Netflix has turned these monsters into iconic, household names, but you probably didn't know that the Demogorgon and Mind Flayer were first conceptualized by small-town teenagers who, before sitting down to finish their homework, would do some cheap artwork for D&D creators Gary Gygax and Dave Arneson in the early '70s. This is just one of the fascinating revelations about the tabletop role-playinggame's history, laid out in the upcoming book Dungeons and Dragons Art and Arcana: A Visual History, by Mike Witwer, Sam Witwer, Jon Peterson, and Kyle Newman.