Possible Clues:

• "That's Not All Folks!" autobiographer
• ''That's Not All, Folks!'' autobiographer
• His headstone says “That’s All Folks”
• Original voice of 50-Down
• Voice of Barney Rubble
• ''Most prolific'' Hollywood actor, per IMDb
• Bugs' voice
• Bugs someone?
• Voice of 1-Across
• His epitaph reads, "That's all, folks!"