Voice actor and kids' TV show host -- via News from Me. He was the voice of Howdy Doody for a year after host Buffalo Bob suffered a heart attack in September 1954. He went on to voice a multitude of characters in Rankin/Bass animated projects. Most memorably for me, he voiced the evil Baron Barracuda and others in the syndicated "Diver Dan":
Never trust a fish with a German accent and a monocle.
And he played Simon Bar Sinister in "Underdog":
UPDATE ON APRIL 27: Here's the belated New York Times obituary --