Historical clue formulations

• 5-Down, e.g., in brief — 2021-11-27
• Head of a country, informally — 2021-05-19
• Veep's boss — 2019-08-11
• Air Force One honcho — 2014-06-17
• Chief exec — 2013-05-22
• W., once — 2013-02-08
• Abe or Ike — 2011-03-30
• Firm honcho — 2009-02-26
• Bossman or bosswoman — 2008-07-20
• Veep's boss — 2006-01-15
• W, for one — 2005-11-27
• Firm honcho — 2005-02-03
• White House resident, informally — 2004-12-15
• White House dweller, informally — 2001-10-16
• "Hail to the Chief" chief — 1996-06-20
• Clinton, slangily — 1994-11-28