Late night talk shows have been around almost as long as television itself. Since the 1950s, late night talk show hosts have entertained audiences with funny monologues, comedy skits, interviews with guests, and musical or standup comedy performances. Along the way, they have shaped the viewing habits of generations of people.

These five past and present late night talk show hosts have done the most to define and build the late night talk show – all while making America laugh night after night:

Johnny Carson

No other host had a greater impact on the rise of the late night talk show than Carson. For 30 years, he was the king of late night TV. Carson's show launched the careers of countless comedians and future talk show hosts. Appearing on “The Tonight Show” with Carson became a status symbol and the quickest way to mass exposure for any celebrity. Carson is still remembered for his sharp one-liners and great comedic skits like Carnac the Magnificent

Steve Allen

Many of the fixtures of the modern late night talk show format were invented by Allen in his stint as the original “Tonight Show” host. Allen pioneered many features such as having an opening monologue, doing celebrity interviews, having musical numbers, and comedy sketches all the while encouraging audience participation.

David Letterman

When Carson begin to rely more frequently on guest hosts, Letterman rose from obscurity as a regular guest host for his show. He eventually was rewarded with his own show following Carson but later left NBC and moved to CBS when he was not named as Carson's successor. He has remained a staple of late night TV for more than three decades with iconic comedy bits like the Top 10 list, Stupid Pet Tricks, and the CBS Mailbag.

Jay Leno

For two decades, Leno has enjoyed success as Carson's successor on “The Tonight Show.” He has also generated controversy with how he beat out Letterman for the job and later forced out temporary successor Conan O'Brien when he decided to return to his old job. Still, Leno has proven popular with his Headlines and Jaywalking segments, which focus on the stupidity of media and the average person on the street.

Jon Stewart

One thing is obvious about Jon Stewart. No other talk show host has had as much of a direct impact on U.S. Politics. While hosting “The Daily Show" Stewart's satirical newscast has influenced voters and, at times, the passage of key legislation. Much of the time, it simply lampoons politicians and politics in a hilarious manner but also served as a vehicle for launching the careers of actors and comedians like Steve Carrell and Stephen Colbert.