Related Clues:

• Mr. Hyde, for one
• Mr. Hyde, e.g.
• Clark Kent, for one
• Hyde, to Jekyll
• Bruce Wayne, to Batman
• One of the 'three faces of Eve'
• Trusted friend
• Perfect substitute
• Mr. Hyde, to Dr. Jekyll
• Close friend
• Evil twin, perhaps
• Bosom buddy
• A different you
• The Lone Ranger, to Tonto
• Holmes to Conan Doyle, e.g.