John Candy, Jim Belushi, Chris Farley, and especially Karen Carpenter. I was living in Los Angeles when Belushi and when Karen Carpenter died. Words cannot adequately express my feelings about the loss of these young, talented people. I still get teary eyed when I hear the Carpenters' music.
I miss Red Skelton, Sam Kinnison, and Phil Hartman too. It seems that when a comedian dies, a bit of the laughter dies right along with them.