In 1962, Johnny Carson took over and stayed until 1992, with announcer Ed McMahon as sidekick, and Doc Severinsen as bandleader. Carson, McMahon, and Severinsen retired from The Tonight Show in 1992, when Jay Leno became host. Leno left the show in 2009, and Conan O'Brien (of Late Night and Saturday Night Live fame) became host from June 2009 to January 2010 before leaving due to controversy with The Tonight Show's timeslot. Jay Leno became the host of the show again on March 1, 2010. Leno retired in 2014 when Jimmy Fallon took over.
Johnny Carson was 36 years old when The Tonight Show starring Johnny Carson debuted in October 1962. He would turn 37 later in the month. Jimmy Fallon was 39 years old when The Tonight Show starring Jimmy Fallon debuted in February 2014. So, as you can see, Carson was the younger host. For the record, Steve Allen was the youngest host, 32 years old when he launched Tonight. Conan O’Brien was the oldest at 46 years old when his Tonight version debuted.