Originally kicked off by Steve Allen half a century ago, The Tonight Show remains iconic television. NBC’s show and format was made most famous by Johnny Carson during his run in the 60s, 70s and 80s, and subsequently infamous by Jay Leno and Conan O’Brien. Leno who was taken on board, dropped, taken back, and dropped again over his 22 years as a host, while O’Brien lasted less than a year.