Historical clue formulations

• Ghostly apparition — 2023-03-08
• Unreal — 2013-12-20
• Universal Studios role of 1925 — 2013-10-31
• *B'way hit beginning in '88 — 2008-10-23
• Not really there — 2007-03-20
• Unreal — 2003-05-17
• Long-running Broadway musical, familiarly — 2001-05-13
• Not really there — 2000-09-28
• Illusory — 1999-10-08
• Not real — 1997-11-28
• Imaginary — 1997-07-20