Wired:

Gygax designed the original D&D game with Dave Arneson in 1974,
and went on to create the Dangerous Journeys and Lejendary Adventure
RPGs, as well as a number of board games. He also wrote several fantasy
novels.

“I don’t think I’ve really grokked it yet,” said Mike Mearls, the
lead developer of the upcoming 4th edition of Dungeons and Dragons. “He
was like the cool uncle that every gamer had. He shaped an entire
generation of gamers.”