DH used to work in theatre so has met lots of stars. His faves were the Attenboroughs (David and Richard, both utterly charming, generous and soooo interesting - DH actually cried when Dickie passed away) and Derek Jacobi who showed a real interest in DH's job and was a total luvvie but in a nice way. Michael Ball absent-mindedly burped right in his face once and was very apologetic afterwards. 
Ooh we've both met Alan Rickman who was completely lovely - always at the theatre, remembered names and faces, chatted to ushers about their drama school ambitions, went full on Snape for tiny Harry Potter fans etc. Almost every theatre actor I know has a story about Alan Rickman sending them a cheque to help with drama school costs / introducing them to a director / coming to their showcase etc - very generous man.
So glad to see others agreeing re: Will Self. He really was incredibly kind to me and inspired me to be a better, more confident person.
My Dad met Angelina Jolie through work and said she was lovely, quite serious and a very hard worker, and made the effort to learn everyone's name.
Bill Oddie is always on these threads but he has severe social anxiety and has apologised a lot for the way he is in public encounters. I feel a bit sorry for him.
Andrew Lloyd Webber absolutely IS an arse. Friend used to work with him and he was a total nightmare in ways I couldn't outline because the thread would end up getting deleted. But very demanding and nasty.
I met Frank Turner a couple of times before he was famous and he was a total arse with HORRIBLE politics. Seems like he's changed!