Historical clue formulations

• Co-star of a #1 TV show for four seasons in the 1950s — 2017-02-24
• Bandleader who popularized the conga line — 2016-07-17
• 1940s-'50s film/TV star with two stars on the Hollywood Walk of Fame — 2008-08-28
• Bandleader/TV star of old — 1996-07-02