Mark Hamill
To many people he is known as “Luke Skywalker” from the Star Wars movies. But he is just as famous for providing voices for animated shows and video games. His most famous voice over work is for The Joker from the animated Batman episodes.
When appearing at many different conventions, whether it’s sci-fi, comic book, movie or a TV convention, Mark Hamill always gets asked to say a couple lines in the voice of Joker from his work on the animated Batman shows.
When Hamill does speak in character for his fans he asks them to turn around and not face him. This is to not break the “illusion” of Joker so the fans see the character in their head when they hear the voice, and not to think of Mark Hamill when they hear it.
I think this example shows Hamills dedication to his work and his pride in what he does. I haven’t heard of any voice actor ever doing this to a fan when asked to voice a certain character and I think it is just amazing.