Even among gamers, Dave Arneson is not a household name. Along with partner E. Gary Gygax, who died last year, he created the first roleplaying game, Dungeons & Dragons. He died a few days ago, on April 7th, 2009.
Unfortunately, while I was aware of his name and his role in the industry, I never knew him very well. There are several bloggers and writers who did, though. I encourage you to Google "Dave Arneson" to see all the obituaries and reminiscences of people who have met him and worked with him. Just based on what I've read over the last few days, he has made quite an impression on those who met him.