A couple years ago, my band played a show at Don Ho's Restaurant in Hawaii. He's a famous old Hawaiian singer (look up 'tiny bubbles') who died not too long ago. While we were playing he showed up with a bunch of old guys and they all danced to our set.
I also met the lead singer for The Bled when about 5 years ago and didn't know who he was.
Went to a Rufio show and got to talk to the whole band at the merch table for a minute, they all seemed pretty quiet but nice.
And I ran into the drummer for Fall Out Boy at Warped back before they were famous. He was really cool.