Who is the most famous person you've ever met?

Got asked this question in the pub on Saturday night and it really got me thinking. My answer in my somewhat intoxicated state after thinking was 'erm....I once played pool against Mark from Eastenders in the 90's'. When I thought about it the next day I totally forgot I saw Frank Skinner last year and said hello to him as he passed and he said hello back. That counts! Who is the most famous person you've met and when I say met I mean at least a hello from them not just being in the same room.