"'The Tonight Show' has a remarkable history rich in tradition.

"The Tonight Show" continues to be the most dominant late-night institution in television history.

Since it first premiered on September 27, 1954 with Steve Allen, "The Tonight Show" has had just four permanent hosts, including Leno.

Allen, host of the then titled "Tonight," eventually left late night to start his own primetime variety series on NBC.

Jack Paar premiered on July 29, 1957.

On October 1, 1962, Johnny Carson stepped on stage for day one of his tenure as host of "The Tonight Show Starring Johnny Carson.

" Leno, who began guest-hosting "The Tonight Show Starring Johnny Carson" in September 1987, became host of "The Tonight Show with Jay Leno" on May 25, 1992.

O'Brien joined NBC as a writer on "Saturday Night Live" in 1988 and premiered as host of "Late Night with Conan O'Brien" on September 13, 1993.