You know this face...

You know this face, but what's the name?

• He was the voice of Chester on the radio version of Gunsmoke.
• He was Darby, a friend of Ozzie & Harriet, on their television show in the 1950s and 1960s.
• For a while, he was the Mayor of Mayberry.
• He was the voice of the Keebler Elf in television commercials of the 1980s.

What's his name? And what else do you know about him?