Historical clue formulations

• Criminal mastermind — 2025-08-23
• One with bright and dark sides — 2023-10-20
• Difficult-to-outsmart villain — 2022-12-13
• One who might cackle "Mwa-ha-ha-ha!" — 2019-08-30
• Enemy who's difficult to outsmart — 2019-05-11
• Lex Luthor, for example — 2015-10-05
• Professor Moriarty, for one — 2005-11-19