My husband used to be a film extra, years ago. He shared a cig with Malcolm Stoddard (not so well known now as he was in the 80s) who he really liked. He was once bought a pint by Timothy Spall - not when he was an extra but when he was in the audience of something at the RSC and they bumped into some of the actors afterwards in a pub. He also said the bloke who plays David in The Archers was lovely.
I was once on a train in the same carriage as the woman who plays Lizzie in The Archers. (I only recognised her as I remembered her from a TV adaptation of 'Pride & Prejudice' I think it was and I happen to loathe The Archers and the cow they rode in on). She spoke so loudly on her mobile, the whole way from London to Bham on the train, the entire carriage could hear every ego-affirming word of how wonderful she was. And even only hearing one side of the loud conversation, she came across as a prat. She looked gutted no-one recognised her.
Years ago I walked right past Ian Holm in Bham Reference Library (he was playing at the theatre at the time, not long after or before 'Alien') and he looked like he wanted the ground to swallow him up - very shy and self-effacing. No-one else seemed to clock him at all, even though it was a crowded place. I just made eye contact and smiled.
Living in Bham in the 1980s, I saw loads of famous people in the vicinity of the TV studios and had a friend who worked at Central TV. He told me Kylie was banned from the studio, forever, for being a diva. (In her defence she was very young, it was right at the start of her trajectory - I suspect she is lovely, now). Saw many Crossroads actors. The one who played Jane literally stopped the traffic on Corporation St to go in a dept store.
Oh my husband met Father Jack from Fr Ted and said he was lovely. Also, he met Harold from Neighbours, and said he was a really decent bloke, too. I forget who but someone we know met Tony Robinson and said he was all over the ladies - around the time he was on TV going on about being a christian. I know a lot of people who work in the heritage industry so can't remember who told me that. Apparently he chatted up anything female that wasn't nailed down.