1. Don Herbert: Dead
You probably know him as Mr. Wizard. After a distinguished stint as a bomber pilot during WW2, Mr. Herbert returned to the states where he worked on educational radio programs for children in the late 1940's. During this time he was working on a concept for a show that would promote the wonder of science on the newish television medium. In 1951, this show idea became Watch Mr. Wizard, a program which was eventually broadcast on over 90 stations across the country and spawned a 50,000 member strong childrens' science club.
2. Mr. Wizard's World
Watch Mr. Wizard's success lasted until its eventual cancellation in the mid 1960's After this Don Herbert began writing science books and making educational films for schools. In 1984 the burgeoning children's cable channel, Nickelodeon, approached Mr. Herbert to produce a new show based on his previous work. This resulted in Mr. Wizard's World, the incarnation probably most familiar to this site's visitors. The Nickelodeon show continued until 1990 and was still shown in reruns as recently a 2000.
3. Sit Down
In 2005, the Academy of Television Arts & Sciences conducted an in-depth interview with Don Herbert. It seems his hearing is pretty much shot at this point, which might explain why his show ended when it did.
4. Sit Down
Still it is pretty interesting to hear about his early days and the multiple shows and other science programs he worked on.
I'm just going to hope that you have 2 hours to spare so you can watch the whole interview even though, by the end of the interview he seems a bit fed up with the whole thing and even a little bitter about his career. I hope he knew how important he was to generations of young people.