Don Herbert, aka "Mr. Wizard", died June 12, 2007 after a battle with cancer.
The original Watch Mr. Wizard aired from 1951 through 1964, facinating young viewers with the delights of science by demonstrating experiments using household items and encourage kids to "try this at home." The show was revived in the 1970's and again in the 1980's when Herbert retooled the show, speeding up the pace for the Nickelodeon channel.
Go here for more info. Below are clips from the Nickelodeon show.