While there are so many actors and pop-culture icons who added to the beauty of this show, being a huge Star Trek geek, I have to go with the cast that participated in the episode Where No Fan Has Gone Before
Honorable mention to Bea Arthur as Femputer.
Great mentions!
Al Gore's appearances always make me laugh.
"I have ridden the mighty moon worm!"
I can tell you where we're not! And that's the universe!
Peace out, y'all!