This is a tough question, and I don't want to sound like some kind of lunatic describing every single one...so I'll be brief:
--Gary Mauer and Beth Southard at THE PHANTOM OF THE OPERA on tour (my friend accidentally left her T-shirt inside, so I waited at the stage door for her, and ended up having a long chat with Beth Southard about the show and studying theatre).
--OBC of CURTAINS (most of them, at least. My first time in NY, and the 2nd show I had seen on Broadway. Everyone signed over their character's box on the poster...except David Hyde Pierce...who didn't come out before our group had to leave...Random story: we found out AFTER returning from our trip that one of the girls in our group is a distant relative of Karen Ziemba! Two months later, her dad is in NY for business, and was able to arrange it so he & his clients could go backstage with Karen and meet David...of course...)
--Chip Zien at LES MIZ (I didn't even know he was in the show until I opened my Playbill. He was so nice at the stagedoor, and even posed a second time for a photo that my friend screwed up. Saw this the night before CURTAINS).
--Patti LuPone at GYPSY (I shook her hand...I shook her hand...)
--Kathy Voytko at EVITA on tour (she fell in love with my friend's miniature Sharpie, so she gave it to her. We chatted while walking up the street to the crosswalk, and then went in different directions).
I'll stop now. I promise to narrow it down to one...eventually...but if I had to pick one now, it would be Patti.
Oh, yeah: I got George Wendt's autograph when I saw 12 ANGRY MEN on tour. Sadly, that program has found its way into the darkest corner of a box I cannot find.
-- SDG