text: The Tonight Show is an American late-night talk show that has been broadcast on NBC since 1954. 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). Besides the main hosts, a number of regular "guest hosts" have been used, notably Ernie Kovacs, who hosted two nights per week during 1956–1957, and a number of guests used by Carson, who curtailed his own hosting duties back to three nights per week by the 1980s. Among Carson's regular guest hosts were Joey Bishop,  McLean Stevenson, David Letterman, David Brenner, Joan Rivers, and Jay Leno, although the practice has been mostly abandoned since hosts currently prefer reruns to showcasing potential rivals.