Ernest Gary Gygax ( GHY-gaks; July 27, 1938 – March 4, 2008) was an American game designer and author best known for co-creating the pioneering tabletop role-playing game Dungeons & Dragons (D&D) with Dave Arneson. In the 1960s, Gygax created an organization of wargaming clubs and founded the Gen Con tabletop game convention. In 1971, he co-developed Chainmail, a miniatures wargame based on medieval warfare with Jeff Perren. He co-founded the company TSR (originally Tactical Studies Rules) with childhood friend Don Kaye in 1973.
https://en.wikipedia.org/wiki/Gary_Gygax