My battery is running low so I'll add mine then carry on reading til it runs out! I have a couple:
On holiday in St Lucia in 1989 as a child, Anita Dobson (Angie from Eastenders) was at the same hotel that we were at.
I was good friends with a girl at Uni who had served George Michael and Geri Halliwell in the pub she worked in at her home town.
I was with that same friend when she received an excited phone call from someone at home telling her that she's just seen Robbie Williams in their town and sadly my friend, who was a huge fan, had already made plans to help someone that weekend so couldn't even go home and stabs a chance of seeing him herself.
Another friend - her mum almost got knocked off a pier into the sea by Jim Davidson because he was really rude and arrogant and would not move out of anyone's way.
My mum and dad met Noel Edmunds at a pub event (as in an event for publicans) years ago for Miller Lite.
Less tenuous - I met Michaela Strachen at a Crime Prevention conference when I was 14. I have met most of the cast if Buffy the Vampire Slayer, Angel and Firefly.
Im sure there are more, ridiculously tenuous ones so I'll have a think!