I was watching the Stargate: Atlantis finale last night and they made mention to General Hammond, played by Don. S. Davis, passing away. I thought it might be because he just wasn't able to make it to production for some reason. They didn't have Richard Dean Anderson on, either.
After it was done, I checked IMDB and, sure enough, Don passed away June 29 of 2008. I knew he had originally left Stargate: SG-1 for health reasons but I completely missed that he'd died this year.
I met him once, as you can probably tell by the photograph (we're leaning over a table). Unfortunately that's about all of the interaction I got with him. Shortly after that shot was taken I had to leave for Kansas City to help celebrate my parents' 40th wedding anniversary.