i've met a few at Cons etc, i never get into much dialogue w/ people as i'm pretty shy but you can tell from watching them whilst in the queue who are the ones genuinely interested in the fans etc.
Dave Prowse - met him as a kid when he was the Green Cross Man ~ that was before he was seduced by the dark side :-D
Claudia Christian - total honey, very nice and damn pretty
Dario Argento - at a horror fest in London, he signed a few autos, then when the lights went down for the next film he just moved off to one side and stayed until everyone had gotten their stuff signed.
Lucio Fulci (RIP) and David Warbeck - as a fest in London. both AWESOME guys. LF had his foot in plaster from an injury, but they did the Q&A, film intro etce etc. in the bar for the signings, they just signed *everything* (LF signed a book of mine several times on different pages :-D ) and believe me, some fanboys had armloads of stuff. DW was great, signing and chatting for ages, real nice friendly guy, had a laugh w/ people at some of the daft stuff he's done on screen etc.
Charisma Carpenter - O-M-G. If you thought she was pretty in Buffy/Angel, you need to see her IRL. :loveShe had her long hair back and was just flat-out stunning. very very good w/ the fans too, signed like a fricking machine.
Adam Baldwin, Ron Perlman, same event - both nice, didn't talk to them much but they were both cool w/ the fans. Val Kilmer was supposed to be there too, he was a main reson i'd gone, but he no-showed. Something about one of his stalkers having been spotted at the event :-/
Kelly Hu - very nice. gorgeous.
Amber Benson : as per Charisma, beautiful on every level. delightfully pretty and very nice.
Joss Whedon - nice guy, tried to talk and sign etc but ended p having such a queue etc that the wizard con staff ended up capping people to 3 autos each etc. still, i asked if he wouldn't mind signing 4 (i had stuff for friends) and he said no bother.
Kev Smith i just saw when he was doing a sale at the comic art auction in Chicago one year. he got into a bidding war w/ a guy himself and was very funny. A freind of mine jumped into his limo when they were pulling up and he was pretty cool w/ it - the fact she was a total beaut mighta beena factor tho :-D
Stan Winston (RIP) - was at Chic one year. He was at a booth and virtually no one was around. i said hi and how much i loved his stuff etc, he was very nice and friendly, seemed pretty unassuming and humble too. wish i'd talked a lot more to him, but i'm shy.
most others i've met have been comic guys. Met a load who worked at Chaos when i went to the cons/fests. Rich Larson is great too, so is Kyle Hotz.
Met Iron Maiden a couple times, once after a gig they opened the hall up again and let us in, and signed everything for everyone. Blaze of Wolfsbane was hanging about too, having a laugh and carry on w/ the fans, he went in too! Steve Harris was like "don't i know you?!" "Yes, i'm in the support band!"
Saw Danzig after a gig, was just sitting in the bus doorway chatting and signing, was very calm, cool and fan-friendly.
Got a meet and greet ticket for Alice Cooper a few years back - absolute top notch gent. Can't say enough, he's just so friendly, humble, a great laugh and so entertaining. Was great w/ photos and signings, not paying much attention to the number-of-items-limit stipulation etc that had been on the ticket conditions. going for a M&G again this year on Hallowe'en, i'm going in costume as Severen from Near Dark so hopefully he'll get a kick out of that.
Never really had a bad incident that i can think of, loads of people said Todd McFarlane was a fkwit though.
mate met Crispin Glover when he did a signing at the local fleapit film night thing, says he was phenomenal, great to chat and talk to, he's done a few books (on films, i think?) and he gave my mate a full set, and signed them.
another mate did the security for Y2J at a local comic shop, said he was a total pro, extremely friendly and accomodating. I've heard that of virtually all the top-rank WWE people, actually.