At the dawn of the TV era, Steve Allen's zany spontaneity turns "Tonight" into an unexpected hit. But in the early 1960s, Jack Paar's quirky personality and Johnny Carson's impeccably hip humor transform late night into an enduring television staple.

Johnny Carson deftly navigates the turbulent 1960s to elevate "The Tonight Show" and become the undisputed king of late night. But success begets competition with the emergence of other hosts, including an Indiana weatherman named David Letterman.

As the 1980s dawn, David Letterman reinvents late night comedy for a new generation, rescuing comedian Jay Leno's nearly flamed-out career in the process. But Johnny Carson's enduring comic appeal spawns endless speculation over his eventual successor.

Carson's 1992 retirement touches a nation, and touches off an epic late-night war between Jay Leno and David Letterman. But it's newcomers Conan O'Brien, Jimmy Kimmel and Jon Stewart who change late night's sense of humor forever.

As the 2000s unfold, Jay Leno's monologue mastery captivates mainstream America. But his succession struggle with heir-apparent Conan O'Brien is no joke, making waves across the late-night landscape and bringing Jimmy Fallon's fresh voice to the front.

Jimmy Fallon takes over for Jay Leno, Stephen Colbert inherits David Letterman's desk, and Trevor Noah becomes a surprise pick for Jon Stewart's replacement. Plus, new hosts James Corden, Seth Meyers and Samantha Bee join the late-night TV ranks.