Possible Clues:

• Murderous Mr. of fiction
• Literary alter ego who inspired the Hulk
• Evil half of a Stevenson character
• ___ Amendment, controversial 1976 Congressional measure
• Monstrous Mr
• Sinister literary Mr
• Anne --, mother of the monarchs Mary II and Anne
• Jekyll's 12 Down
• 'Pure evil,' per Jekyll
• Misanthrope of Victorian literature