Historical clue formulations

• Chess great Spassky — 2025-08-01
• First name of Russia's first president — 2025-04-13
• First name of Russia's leader, 1991-99, and of Britain's leader, 2019-22 — 2023-09-23
• Name of three czars of Bulgaria — 2023-08-11
• First name of Russia's first president — 2019-08-15
• Foe of Rocky and Bullwinkle — 2016-07-26
• ___ Johnson, former mayor of London — 2016-07-17
• London mayor Johnson — 2012-11-06
• Czar of Russia between Feodors — 2010-07-07
• Cartoon villain Badenov — 2008-02-12
• Czar in a Mussorgsky opera — 2006-05-28
• Title character in a Pushkin drama — 2003-10-30
• Mussorgsky bass — 2001-04-15
• Mussorgsky's Godunov — 2000-02-15
• Villain for Rocky and Bullwinkle — 1999-11-18
• Pushkin hero — 1997-07-30
• Tennis's Becker — 1997-05-28
• First name in the Kremlin — 1996-10-02
• Enemy of Rocky and Bullwinkle — 1995-01-19
• Bulgarian king, 1918-43 — 1994-07-01