The program has been hosted by six comedians: Steve Allen (1954–1957), Jack Paar (1957–1962), Johnny Carson (1962–1992), Jay Leno (1992–2009 and 2010–2014), Conan O'Brien (2009–2010), and Jimmy Fallon (2014–present).

From 1950 to 1951 NBC aired Broadway Open House, a nightly variety show hosted primarily by comic Jerry Lester.

Allen's version of the show originated talk show staples such as an opening monologue, celebrity interviews, audience participation, and comedy bits in which cameras were taken outside the studio, as well as music including guest performers, a house vocal group (duo Steve and Eydie, who would marry each other in 1957) and a house band under Lyle "Skitch" Henderson.

To give Allen time to work on his Sunday evening show, Kovacs hosted Tonight on Monday and Tuesday nights with his own announcer (Bill Wendell) and bandleader.

She would continue to perform the same service for most of the major talk shows for decades, including those hosted by Paar, Carson, Merv Griffin (until 1986), and Mike Douglas, among others.

A combo band conducted by Paar's Army buddy pianist Jose Melis filled commercial breaks and backed musical entertainers.

On February 11, 1960, Jack Paar unexpectedly walked off the show in the midst of the program – an absence that lasted almost a month – after NBC censors edited out a segment taped the night before about a joke involving a "WC" ("water closet", a polite term for a flush toilet) being confused for a "wayside chapel".

She asks about the location of the "W.C."  The Swiss, thinking she is referring to the Wayside Chapel, leaves her a note that said (in part) "the W.C. is situated nine miles from the room that you will occupy.

Among those appearing in taped farewell messages were Richard Nixon, Robert F. Kennedy, Billy Graham, Bob Hope and Jack Benny.

After a brief stint by Milton DeLugg, beginning in 1967 the "NBC Orchestra" was then headed by trumpeter Doc Severinsen who had played in the band during the Henderson era.

Carson's ratings usually substantially led his timeslot, in spite of the fact that he intermittently faced many other late-night competitors including Les Crane, Bill Dana, David Frost, Regis Philbin, Alan Thicke, Jerry Lewis, Joan Rivers, David Brenner, Pat Sajak, Ron Reagan, Dennis Miller, and most notably Steve Allen, Arsenio Hall, Joey Bishop, Merv Griffin, and Dick Cavett (Carson saw his friend Cavett as his real competition but Cavett was on ABC, a much smaller network at the time).

On May 22, 1992, Johnny Carson retired after three decades behind the iconic late-night desk, and was replaced by Jay Leno amid national and media controversy.

[7] Letterman, having had his heart set on the earlier time slot in spite of Leno's ratings success as recurring substitute host, left NBC (on Carson's advice) and joined rival network CBS.

After a strong debut week, O'Brien's total audience fell precipitously over the summer months, and the program began losing to Late Show with David Letterman in overall ratings.

This would move The Tonight Show to 12:05 a.m., a post-midnight start for the first time in its sixty-year history, while Late Night with Jimmy Fallon would be pushed to 1:05 am, and Last Call with Carson Daly would likely be cancelled.

[19][20] TMZ reported that O'Brien was given no advance notice of this change, and that NBC offered him a choice: The Tonight Show in a 12:05 a.m. time slot, or the option to leave the network.

[23] Leno was criticized for his remark, which contradicted his statement that "I think Conan is doing fine" mere months earlier,[24] after which O’Brien's ratings were on an upward trend.

After the decision was made to reinstate Leno, NBC executives and Leno maintained in the media that O'Brien's ratings were responsible for his removal from the traditional Tonight Show time slot, while O'Brien's supporters argued that the incumbent host had been denied the unambiguous transition, network support and time to grow that his predecessor had received.

O'Brien's rating surge during the controversy was also seen by some of his proponents as having the potential to be the host's "Hugh Grant moment" – an allusion to a 1995 interview on The Tonight Show with Jay Leno that aired shortly after the British actor had been caught publicly soliciting a prostitute.

The New York Post advanced a theory that O'Brien being the cheaper host to lose was the cardinal factor in NBC's decision to negotiate his departure.

[29][30][31] O'Brien returned to late-night television on November 8, 2010 (after his non-compete agreement expired), hosting the self-owned Conan on cable channel TBS.

[39] In August 2012, The Los Angeles Times reported that The Tonight Show was in trouble for a number of reasons, notably that NBC was losing money.

Leno gave a tearful goodbye at the end of the program, calling himself "the luckiest guy in the world", and reflecting on his time as host as "the greatest 22 years of my life.

Fallon's Tonight Show has gone on the road to produce episodes remotely in its first year, spending four days at Universal Orlando Resort in Florida in June 2014 to promote new attractions at NBCUniversal's theme parks there.

Skitch Henderson was the bandleader during the Steve Allen and early Carson years, followed briefly by Milton DeLugg (who had previously led the band on Broadway Open House and later became the musical director of The Gong Show).

On the rare occasions that both McMahon and Severinsen were away, Newsom would take the announcer's chair and the band would be led by assistant musical director Shelly Cohen.

Jimmy Fallon began hosting The Tonight Show on February 17, 2014; his house band on Late Night, The Roots, joined him, as did announcer Steve Higgins.

[58] The Tonight Show became the first American television program to broadcast with MTS stereo sound in 1984, at first sporadically, by audio engineer Ron Estes.

In September 1991, the show's start time was shifted by five minutes to 11:35, in order to give network affiliates the opportunity to sell additional advertising during their late local newscasts.

On the October 23, 1984, broadcast, guest Paul McCartney had this to say of the show's British run: Carson: (throwing to commercial) OK, we're gonna have to cut away.