I have met a whole hell of a lot of bass players, which is kind of odd because I only kind of dabble in bass, but I play guitar.  
Also odd I think is that of what is about to be a very long list, I don't really 
know any of these folks.  As in... we're not buddies.  Nobody's given me their cell number, you know? But I've met every one of them.
Bass PlayersDoug Wimbish  twice, about 15 years apart.  Once in D.C., once in New York
 Dave Ellefson  JD DeServio Tony Levin  Leland SklarRode in an elevator with 
 Stu Hamm  Chuck Rainey Other MusiciansI Drove 
 Tim Alexander  around D.C. in a lowrider I used to own and eventually dropped him off at his hotel
I've been in the dressing room of the old 930 club with 
 Sick of it AllAlso at the old 930 I talked briefly with 
 Nivek Ogre I've met all the guys in Fugazi, Skeeter from Scream, met the Bad Brains, the Cro-Mags, and lots of other even lesser known bands.
I worked briefly in the early 90s at a club in D.C called 
 The Bayou.  Met a ton of the acts.  Hell, the first night I worked there White Zombie was playing.  Approximately eleven and a half billion shitty college metal bands came through while I was there, as well as Sophie B. Hawkins, Lynch Mob, LSD, and Jackal.
ActorsI spent about five minutes talking with 
 Stacy Keach  when I was about 17, and when I was ten or eleven I stood in line at the local video store to get 
 James Doohan  to autograph a comic book.
Favorite 'famous' guyAbout a year before he died, I got to meet 
 MSG Roy Benavidez .  He was the great uncle of a guy that worked for me at the time and was just soooooo cool.
*whew*  I think that covers it.