When I was a freshman in college I was a member of the University Union, which among other things, brought guest speakers to campus. We got Leonard Nimoy to come (this was in 1984 during a lull between Trek movies and other projects).
He gave a great talk to several hundred students, then, although he was visibly tired, took six or eight of us from the Union back to his hotel lounge with him. We all sat and chatted with him for well over an hour, and found him to be friendly, intelligent, and interested in who we were and what we had to say.
I’ve also met and corresponded many times with Neil Gaiman. He’s a nice fellow, if a bit of poseur (he never takes off his sunglasses).