So ... I live in NYC, so have a fair number of fun interactions. Still, here are a number:
1) Brooke Shields: In the early to mid-1980's when I was in college or just out, I was on Amtrak coming North from the South, and a tall, slender, strikingly pretty young woman with very heavy eyebrows got on the train with a heavy duffel bag, and sat in the open seat next to me (I was on the aisle - for leg room, and she wanted the window seat). I help her put her duffel in the rack above us, and on and off for the next hour talked to her, until the train arrived in NYC. I never asked her name, and she never offered it, but it was clearly Brooke Shields ... I am pretty sure she was more comfortable talking to a stranger her own age (well I was a couple years older - she was at Princeton and may have been only 19 or 20 at the time) when that person did NOT impose on her pr press her for her name. I do remember her talking a lot about her half/step siblings, especially about her brother.
2) Heidi Klum and Seal: Heidi lived in the same building in which my apartment is, and after she met Seal he lived there also. I had numerous conversations with her and Seal, have had drinks in her apartment, once when struggling with both my young kids and several bags of groceries enjoyed Seal (the nicest guy, by the way) coming into the building at the same time, and scoop up both my kids (he is a big guy) and help me into our apartment. We were not friends, but I would say we were more than casual acquaintances.: True neighbors.
3) Antonio Fargas (Huggy Bear on Starsky and Hutch): Okay, not a major star, but even so ... Was on a cross-town bus in NYC across from him, and I greeted him, telling him I enjoyed him in Starsky and Hutch. He was delighted, saying, "How nice - no one ever recognizes me , so thank you for saying hello."
4) James Gondolfini: Met him while he was playing with his toddle kid in the local playground. My young kids were in the playground as well - I merely said hello when his kid and mine were all in the sandbox together. He was friends with a friend of our in the neighborhood and was visiting the neighborhood. Around the same time, Ricki Lake also spent a fair bit of time with her kid at the same playground.
5) Julianne Moore: I often saw her walking in my neighborhood - but that is a sighting, not an encounter. So ... her son played basketball (was a preferred walk-on at Davidson, FYI). He also played high school basketball in NYC - playing against my son's high school team each season (out of conference). At one game, I was in the stands having an enjoyable conversation with a parent from the opposing team, we were next to each other in the bleachers ... and of course, asking which player was her kid, and she asking which was mine, and both of us complementing each other's son ... Her son was WAY better than mine, BTW - he was the star on his team while my son. though he played a lot, was just the 6th man on his team. We talked for more than an hour. After the game, my son came up to me all excited and asked what Julianne Moore was like . I asked why he asked, since I did not know her. He looked me like I was an idiot (which I was, of course - being a parent of a teen) and told me I had been talking to her all game, LOL! I was completely oblivious, just focused on the game, and sharing the game with another parent. Yes, what an an idiot I am! When I did see her in the neighborhood a couple of times I did greet her - and she did remember who I was.
6) Hugh Jackman - and his now soon to be ex-wife, Deborah: This is a good one. A friend invited us to a benefit on hunger (it turned out it was the organization that had pulled in Deborah and Hugh - it was really Deborah's thing more than Hugh's). Anyway, they were both there, of course. At the cocktail hour, my then wife kept staring at Hugh - who she reminded me lived in our neighborhood. I encouraged her to go say hello, and we both walked over (me giving my wife moral support). When she introduced herself as neighbors, Hugh lit up abd called HIS wife over and we talked for the next 10 minutes or so. THEN ... the very next morning, my wife was walking our dog, and ran into Hugh walking HIS dogs (they had 2). He immediately recognized her and came over to give her a hug and a kiss on the cheek - made her day. We ran into Hugh many times over several years, and sometimes walked our dogs together ... Those in NYC understand dog-walking culture: Its us against the world, and people get to know their acquaintances' dogs better than the people.
In business, I also had the opportunity to mee many well-know investment world people (once talked to Ivan Boesky on the phone - before his arrest, but later realized it was while he was taping people as a snitch for the Feds - my boss was friendly with Boesky and asked me to pass along to Boesky our technical indicator charts - nothing insider about that, FYI).