The original cool science guy.

Well at least for me. Before Bill Nye and his frenetic energy busted on the scene for me there was only Mr. Wizard. I'm going to sound like an old fogie now but back in the day when Nickelodeon had better content like You Can't Do That On Television and Mr. Wizard's World, my sister and I would watch Don Herbert in awe at his experiments and dead pan explanations which were not condescending despite his younger audience. When he passed away a couple of years ago I was surprised to learn he'd been doing the Mr. Wizard gig for quite a while. Here he is explaining siphons to a young girl.