My name is BigBeads and I have never met Anthony Stewart Head 
Alrighty then, some actual encounters, some observed;
Matt Dillon: Hung out for a bit once years and years ago, he was a total doll. So gorgeous, and very unstarry and good fun. Unlike...
Bono: Giving it the full 'you are in the presence of a ROCK GOD' in a tiny country hotel bar whilst the rest of us studiously stared into our pints and pretended we couldn't see the leather clad midget in heels stomping around in front of us.
Thom Yorke: A good friend of mine tried to get an autograph off tortured genius Thom Yorke*TM once. In fairness, we all told her it was not going to end well, but it was for her little brother so she wanted to ask anyway and she was pissed and yes, it didn't go well.
Gary Barlow (circa Relight My Fire years): giving it SOCKS on a block in Ministry of Sound one night. Gurning like a loon, but then weren't we all 
Jeremy Irons: Spied on a regular basis wafting up and down Grafton St like the next incarnation of Sir John Geilgud. Painful. Whatever Mumsnetter nearly took him out on an escalator, I applaud you! (His wife is smashing though).
Dude who was Billy in Neighbours: once winked at me in a whole 'wassup?' manner whilst I was sitting outside a bar in Melbourne. Infuriatingly none of the three people with me saw this happen. But it did, IT DID!
Princess Anne: She was just, what can I say, a total pro. I was representing a lottery funded charity project that had been built in the arse end of nowhere, and she came in, chatted like billyo with everyone, clearly had done her homework, and then she and I proceeded to have a good bitch about the eejits on Castaway. Or as she put it "As my daughter says "what a bunch of "wusses"". You could feel the air quotes
Never once made anyone there from top to bottom feel like it was anything other than her pleasure to be there. I've had a massive girl crush on her ever since.
SWINTON!: Tilda Swinton sort of gliding towards the first class lounge in Charles De Gaulle. It was almost like seeing an alien she's so 'other'. She's tall but extremely graceful and languid. Adding to the effect was that she was wearing an exquisite off white silk trouser suit that draped 'just so' with an oxblood trilby and matching oxblood leather bag which was nearly bigger than her. DH and I just gazed and gazed, we couldn't help it 