Gygax was one of the most influential people to anyone who considered themselves a geek after 1975 or so.
I met him once, at I-Con years ago, and we interviewed him for The Chronic Rift (drewshi did the interview). He was apparently hosting weekly D&D games right up until the end.
He will be sorely missed.
(Of course, now Al Gore, Nichelle Nichols, and Stephen Hawking will need a new fourth....)