Current players: It's a tie at the moment between Ryan Zimmerman and Danny Hultzen, the best players to come out of my alma mater. Hultzen just got drafted by the Seattle Mariners. The first time I saw him during his first year at UVa, I thought to myself, "That's a ball player." One of the few times I've been right about that sort of thing.
Retired players: Ken Griffey, Jr. (great centerfielder, had the prettiest swing I've seen, and,
AFAIK, did it all above-board during the steroid era) and Joe Pepitone (my first favorite player when I was a kid).
Dead players: Honus Wagner (incredible all-round player and a good guy); Mickey Mantle (would have been the greatest of all time, but for injuries and alcohol); and Babe Ruth (no explanation needed).