I lived in San Antonio for 22 years, and we're all rabid Spurs fans down there because they are the best NBA team ever
I went to see Austin Powers Goldmember opening night at the Palladium, which is kind of a higher class theatre on the north side. Tim Duncan and David Robinson were sitting in the back just chillin. Slowly everyone started noticing and swarmed them to meet and take pictures. I chose not to because I felt kind of bad, they were just trying to watch the movie, I said what's up afterwards. Both were so nice and it was surreal how tall they were. Amazing players.
Where I live now I've seen Dave Chappelle 4 times, and I even saw him with his son at a Smash 4 local. I didn't bother him any of those times because I know he hates the attention. The first time I saw him at the mall I just said "Hey Dave, I love your stand up and I miss the Show!"
I've also got to see Sia before she was all incognito with the wig, it was 2007 at SXSW and she sung "Breathe me" live, it was so beautiful I teared up a bit. I saw her at the bar afterwards but didn't bother her (kinda regret not meeting her)
The last one was Craig Harris (was lead Nintendo editor at IGN for a while, Podcasts, etc) at PAX EAST 2012, I have a picutre with him while he was running the Aliens: Colonial Marines booth and him helping me into the mech walker from Aliens. EDIT - aw yea forgot to say that I got the meet the whole Mega 64 crew (Rocco Botte filmed one of his infamous transitions for me), and I of course met the Penny Arcade creators who ran the show.
There are probably others but I'm forgetting right now. I don't know I don't really obsess over celebrities, and I don't get pics just to say "Hey look who I met, aren't I cool?". The only ones I'd probably bother or go out of my way to meet would be the ones that I think I would have a great conversation with or that would be fun to hang out with (and hopefully they feel the same). There are a ton I admire/like but it would be kind of awkward just to go up and be like "OMG I LOVE YOU AND YOUR STUFF" and then nothing but silence after cause we have nothing else to talk about...
Like Jennifer Lawrence, Ricky Gervais, Trent Reznor, Bill Nye, KassemG, Arin Hanson and some of the OG Newgrounds people. People that I feel I would have interesting conversations with on the same level whether artistically, philosophically, or casually.