I realize not everyone here attended KU, but a lot of did and a lot of famous people have connections to KU either directly or indirectly.
KU's Facebook page shared this story today from back in 2009 about Taylor Swift visiting KU for a day because on of her closest friends was on the swim team then.
Taylor attended some media class with her friend in Budig and I happened to have an anthropology class across the hall at the same time. Even as a history major, anthropology was boring as hell. Word spread very quickly that Taylor was there obviously and I waited outside after class hoping to meet her. I didn't get a picture with her because I couldn't afford a smartphone as they were still extremely new and expensive as hell, but I did get to meet her and tell her we shared a birthday (just not the same year).
My other celebrity encounter was the night that Kirk Hinrich had his jersey retired and I bumped into him on the second level concourse as he was leaving the arena to beat traffic and I was returning to my seat from the bathroom. I was able to get a picture with Kirk that night which was very cool.
If you had any celebrity encounters while at KU, this would be a good place to share those stories.