Possible Clues:

• Malicious one
• One who acts badly as Duke in role I've revised
• 21 Across type always assuming one left party
• Invariably imprisoning one old-fashioned offender
• Deliver love letters? This can be criminal!
• Back live at the party with 'er baddie
• Villain lied over running amok
• The Joker or The Penguin
• Wicked one
• Bad person wrongly reviled, hiding nothing