Possible Clues:

• 'The Man of a Thousand Voices'
• ''Man of a Thousand Voices''
• Impressionist once labeled 'The Man of a Thousand Voices'
• Impressionist once labeled "The Man of a Thousand Voices"
• Impressionist who was frequently a guest of Johnny Carson
• Impressionist whom Mel Blanc labeled "The Man of a Thousand Voices"
• Johnny Carson impersonator of note
• Impressionist extraordinaire
• Great ape?