Who Is The Only Person To Have Played Themselves In The Star Trek Universe?

All manner of famous people have appeared in the various incarnations of Star Trek over the years: Abraham Lincoln, Mark Twain, Genghis Khan, and Albert Einstein to name a few. via Pocket http://www.howtogeek.com/trivia/who-is-the-only-person-to-have-played-themselves-in-the-star-trek-universe/