As pax not crew:
I met Alan Shearer (Current Newcastle Captain, former England Captain) on a flight back from Barbados and he was a complete gentleman.
Met Billy Connolly at LHR and he was as funny in person as he is on the TV.
Shared a plane with Tony Blair to Bermuda and he was quiet throughout the flight. It seemed really strange seeing your Prime Minister sitting in Club World, not first!! You'd never see an American President doing that!!!