I Love Lucy (1951)

Lucille Ball and Desi Arnaz's CBS sitcom (1951–1957) is the foundation of modern American television comedy. It was the first show filmed before a live studio audience using three cameras simultaneously — a production format still used by multi-camera sitcoms today — and the first series to be filmed on 35mm film, making syndication possible. At its peak it was watched by approximately 60 million viewers per week in a country with 165 million people, and its "Lucy Is Enceinte" episode about Lucy's pregnancy was watched by more Americans than watched President Eisenhower's inauguration the following morning.