Historical clue formulations

• "Fear is ___. So are regrets": Marilyn Monroe — 2023-11-04
• One-fourth of KISS — 2021-10-22
• Half-witted — 2015-07-12
• Cry with a forehead slap, maybe — 2011-11-13
• "Keep it simple, ___" — 2008-07-07
• Muscleheaded — 2008-02-15
• Clueless — 2007-02-17
• Blockhead — 2004-07-25